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Which Order Should Columns Go in an Index?: Finding All the Red Sweets Part 4
 
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When you create an index on multiple columns there's an important question you need to answer: In which order should you list the columns? This video looks at some of the factors you should consider to help answer this question. ============================ The Magic of SQL with Chris Saxon Copyright © 2015 Oracle and/or its affiliates. Oracle is a registered trademark of Oracle and/or its affiliates. All rights reserved. Other names may be registered trademarks of their respective owners. Oracle disclaims any warranties or representations as to the accuracy or completeness of this recording, demonstration, and/or written materials (the “Materials”). The Materials are provided “as is” without any warranty of any kind, either express or implied, including without limitation warranties or merchantability, fitness for a particular purpose, and non-infringement.
Views: 3958 The Magic of SQL
Oracle New feature 12c  - Multiple Index on same column in oracle
 
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Oracle New feature 12c - Multiple Index on same column in oracle
Views: 84 Siva Academy
Oracle Tutorial - How to add virtual column in oracle 11g
 
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Hello friends in this video i'm going to demonstrate you how to add virtual column in ORACLE 11g step by step. Oracle 11g supports virtual columns which are derived from the other columns in the table. You can use the virtual columns in your queries, you can index them, you can collect the statistics, etc. There are few restrictions on the virtual columns. You cannot write/insert the data into virtual columns. There is no support for index_organized, external, object, cluster, temporary tables.
Views: 1333 OCP Technology
BITMAP  and  BITMAP JOIN INDEX IN ORACLE explained
 
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The video explains BITMAP and BITMAP JOIN INDEX IN ORACLE and when you should create them on a column. BITMAP INDEXES should be dealt with carefully as they can lead to serious performance issues if the table is updated by multiple processes in parallel. Indexing Basics :https://www.youtube.com/watch?v=0X9bbtwTnuE&t=1095s Star and snowflake Schema :https://www.youtube.com/watch?v=Qq4yhhAk9fc&t=17s
Views: 3056 Tech Coach
Database Design 39 - Indexes (Clustered, Nonclustered, Composite Index)
 
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This video covers the basics of indexes. Indexing is an extremely important step of database design. Without Indexes database queries can take a substantial amount of time and hog system resources. The main two classifications of indexes are clustered and non-clustered indexes. Clustered indexes are usually the primary key and determine how the data is actually stored in the table. These are the fastest and most effective. Non-clustered indexes sort a reference to data that is still fast but doesn't actually determine how the data is structured. The best tip I can give you is to use indexes but don't over use them. Having loads of indexes on columns that are barely ever in a where clause or join can bog down the database. This is because every time the table is updated the index must also be updated! When a database looks through a table for certain where conditions on a column that does not have an index, it does an entire table scan. This is not a good practice for large databases (or even small databases but not as bad). With an index the database will do an index seek and quickly find the data you are looking for. Composite indexes consist of two or more columns within one index. Use these when you plan on using the two columns together for a database query WHERE clause. Learn more about indexes here: https://www.calebcurry.com/blogs/database-design/introduction-to-indexes Donate!: http://bit.ly/DonateCTVM2. Courses for Download: http://www.udemy.com/u/calebcurry/ (Use the coupon code "YouTubeDiscount" without the quotes) Facebook: http://www.facebook.com/CalebTheVideoMaker Google+: https://plus.google.com/+CalebTheVideoMaker2 Twitter: http://Twitter.com/calebCurry Subscribe (it's free!): https://www.youtube.com/channel/UCZUyPT9DkJWmS_DzdOi7RIA?sub_confirmation=1 Amazing Web Hosting - http://bit.ly/ccbluehost (The best web hosting for a cheap price!)
Views: 91399 Caleb Curry
Indexing in Oracle :B-Tree,Bitmap Indexing
 
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This Video is the 1st tutorial in the video series Indexing in Oracle , The video series explains in detail, What are indexes?It's types, what index should be used in which scenario and other important thing in basic terminology. Note :You may want to watch the video with a higher playback speed(1.25 if it suits you more)
Views: 12073 Tech Coach
What Impact Do Indexes Have on Inserts?: Finding All the Red Sweets Part 0
 
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Creating indexes can improve query performance. Oracle must maintain the indexes however. This increases the work it must do whenever you modify data in indexed columns. In this video Chris looks at this overhead using a real world analogy - recording the color of all the candies stored in party bags! ============================ The Magic of SQL with Chris Saxon Copyright © 2015 Oracle and/or its affiliates. Oracle is a registered trademark of Oracle and/or its affiliates. All rights reserved. Other names may be registered trademarks of their respective owners. Oracle disclaims any warranties or representations as to the accuracy or completeness of this recording, demonstration, and/or written materials (the “Materials”). The Materials are provided “as is” without any warranty of any kind, either express or implied, including without limitation warranties or merchantability, fitness for a particular purpose, and non-infringement.
Views: 2604 The Magic of SQL
B-Tree Indexes
 
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In this video, I'd like to take a look at B-tree indexes and show how knowing them can help design better database tables and queries.
A Story of Indexes and Full Table Scans: Finding All the Red Sweets Part 1
 
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"Why isn't Oracle using my index?!" is a common question people have when tuning SQL queries. In this episode Chris compares two methods for finding all the red candies from party bags he's prepared. He shows how these are like a full table scan and an index range scan. He goes on to compare the performance of these two approaches. He shows when a full table scan becomes more efficient than an index range scan and vice versa. ============================ The Magic of SQL with Chris Saxon Copyright © 2015 Oracle and/or its affiliates. Oracle is a registered trademark of Oracle and/or its affiliates. All rights reserved. Other names may be registered trademarks of their respective owners. Oracle disclaims any warranties or representations as to the accuracy or completeness of this recording, demonstration, and/or written materials (the “Materials”). The Materials are provided “as is” without any warranty of any kind, either express or implied, including without limitation warranties or merchantability, fitness for a particular purpose, and non-infringement.
Views: 7773 The Magic of SQL
Oracle Pseudo Column, Virtual Column , Invisible Column and Unused Column
 
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More Details at, Pseudo Column @ https://www.youtube.com/edit?o=U&video_id=GIGmZwShGh4 Virtual Column @ https://www.youtube.com/edit?o=U&video_id=qUALFDzLDJw Invisible Column @ https://www.youtube.com/edit?o=U&video_id=nz48CdgDCt4 Unused Column @ https://www.youtube.com/edit?o=U&video_id=GWo4VcNZo6Y
Views: 100 Siva Academy
Oracle Database Indexes: Myths, Tips and Tricks
 
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In this tutorial, OCM John Watson will - via demonstrations - debunk these myths: Myth #1: Oracle Database does not index NULL Myth #2: A search that includes wildcards can't use an index if the wildcard precedes the string. Myth #3: Oracle will not use a function-based index unless the FBI is coded in the predicate. Myth #4: Indexes always help. The more indexes the better. See http://skillbuilders.com/free-oracle-tutorials for gigabytes of free Oracle video tutorials.
Views: 16137 SkillBuilders
Oracle tutorial : Pseudo columns in Oracle PL SQL (pseudo column)
 
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Oracle tutorial : Pseudo columns in Oracle PL SQL ( pseudocolumn ) oracle tutorial for beginners rownum in oracle This video will show you what is Pseudo columns in Oracle PL SQL. Pseudo columns are likes ROWNUM, ROENUM, ROWID, NEXTVAL,SYSDTAE , USER etc. pseudocolumn examples Oracle tutorial : Pseudo columns in oracle Oracle supports several special-purpose data elements that are not actually contained in a table, but are available for use in SQL statements. Here is a partial list of pseudo-columns in Oracle a)CURRVAL : When using Oracle SEQUENCE values, the pseudo-column CURRVAL returns the current value of the sequence. for example: schema.sequence_name.CURRVAL b)NEXTVAL :When using Oracle SEQUENCE values, the pseudo-column NEXTVAL returns the next value of the sequence and causes the sequence to increment by one. for example: schema.sequence_name.NEXTVAL c)ROWNUM:ROWNUM returns a number indicating the order in which a row was selected from a table. d)ROWID: ROWID returns the rowid (binary address) of a row in a database table. e)USER :This pseudo-column will always contain the Oracle username under which you are connected to the database. f)SYSDATE:This pseudo-column will contain the current date and time. This column is a standard Oracle DATE datatype. The value represents the current time on the server not the client. For more tutorial please visit #techquerypond https://techquerypond.com https://techquerypond.wordpress.com https://twitter.com/techquerypond
Views: 1403 Tech Query Pond
How to transpose column to row in sql
 
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Hi friends today we will learn how to transpose column data into row of table. #transposecolumntorow Oracle database Unbeatable,Unbreakable Platform..
Views: 15429 Oracle World
[Creating Indexes] 3 - Creating an index on computed column
 
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Creating Indexes Given a SQL Server table named Customer_Details and Calc_Area in the ABC_Bank database,you will view and practice how to create a unique index on a computed column using Transact-SQL. 1 - Creating an unique index 2 - Creating composite index 3 - Creating an index on computed column Learn more at : http://www.tutorialspoint.edu.vn/sql-server/162-types-of-indexes/12610-workshop-types-of-indexes.html
Views: 353 little fire
Column Mode
 
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This video is one of many videos series produced by © Hosny Corporation System http://www.hosnysys.com
Views: 481 Mohamed Hosny
SQL: pseudo columns (Rowid/Rownum)
 
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In this tutorial, u'll learn the difference between rowid & rownum..
Views: 30322 radhikaravikumar
Oracle Database11g tutorials 8 || SQL DISTINCT with multiple columns |SQL Distinct with Two columns
 
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This SQL tutorial and Oracle database 11g tutorial for beginners will show how to use SQL DISTINCT keyword with SQL Select clause. This Video is in the continuation of previous video on SQL distinct with one column. In this video we will see How to use SQL distinct with multiple columns and SQL distinct with two columns Tool used in this tutorial is SQL developer. This tutorial series is part of SQL expert exam certification training. If you are preparing for SQL certification you can use my tutorials. This SQL Tutorial is a part of free training. Copy Cloud referral link || Use this link to join copy cloud and get 20GB of free storage https://copy.com?r=j7eYO7 Contacts Email [email protected] Twitter https://twitter.com/rebellionrider Instagram http://instagram.com/rebellionrider Facebook. https://www.facebook.com/imthebhardwaj Linkedin. in.linkedin.com/in/mannbhardwaj/ Thanks for linking, commenting, sharing and watching more of our videos This is Manish From The Code makers
Views: 97738 Manish Sharma
SQL Server 33 - Indexes
 
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Indexes allow us to tell the database that certain columns are columns we want to retrieve commonly. This allows the database to optimize retrieval. Additionally, when we get into the SELECT statement, we will often have to join data from multiple tables. When we correctly add indexes to our tables, we can improve the speed of our SELECT and also our joins. There are two types of Index. One is called clustered and the other is called non-clustered. Clustered indexes determine the actual order of the table. By default this is going to be the primary key column. So when you label a column as PRIMARY KEY, you are also going to be creating an INDEX that is a clustered index. A clustered index is kind of like a telephone book, where the data is right there when you look up a phone number. This means that if you are just making a small database that is only going to store a few things, you may be fine. But more likely than not you are going to want to add additional indexes. When you add a new index, you create a non-clustered index. These things do not actually determine the order of the rows in the table. A way of how you can think of how these work is like an index in the back of a book. The index of the book does not actually contain the data, it just tells you where to find it. What columns do you index? You are going to want every primary key to be indexed. What about foreign keys, are they indexed by default? No, they are not. Of all columns, you are probably going to want to index the foreign keys the most because they are used in joins. Lastly, you will likely want to index columns that you are going to use on a regular basis. You can also make composite indexes just like you can make composite keys. You would want to do this when you are going to constantly being using those columns together. There is a lot to learn on multicolumn indexes. We may explore this concept in more detail and see how SQL Server uses them in a future video, but as of right now it's probably more important that we get a general understanding of all things SQL Server before we deep dive on something like that. In the upcoming videos I'll be teaching you how to create indexes. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Support me! http://www.patreon.com/calebcurry Subscribe to my newsletter: http://bit.ly/JoinCCNewsletter Donate!: http://bit.ly/DonateCTVM2. ~~~~~~~~~~~~~~~Additional Links~~~~~~~~~~~~~~~ More content: http://CalebCurry.com Facebook: http://www.facebook.com/CalebTheVideoMaker Google+: https://plus.google.com/+CalebTheVideoMaker2 Twitter: http://twitter.com/calebCurry Amazing Web Hosting - http://bit.ly/ccbluehost (The best web hosting for a cheap price!)
Views: 8162 Caleb Curry
ROWID VS ROWNUM IN ORACLE
 
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This Video explains the difference between ROWID and ROWNUM using real project examples. ROWID provides the unique physical address where the row is being stored. ROWNUM indicates the order in which the data was returned from the select query.
Views: 2299 Tech Coach
01 Overview of table Partition in oracle
 
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Partitioning enhances the performance, manageability, and availability of a wide variety of applications and helps reduce the total cost of ownership for storing large amounts of data. Partitioning allows tables, indexes, and index-organized tables to be subdivided into smaller pieces, enabling these database objects to be managed and accessed at a finer level of granularity. Oracle provides a rich variety of partitioning strategies and extensions to address every business requirement. Moreover, since it is entirely transparent, partitioning can be applied to almost any application without the need for potentially expensive and time consuming application changes. Partitioning allows a table, index, or index-organized table to be subdivided into smaller pieces, where each piece of such a database object is called a partition. Each partition has its own name, and may optionally have its own storage characteristics. From the perspective of a database administrator, a partitioned object has multiple pieces that can be managed either collectively or individually. This gives the administrator considerable flexibility in managing partitioned objects. However, from the perspective of the application, a partitioned table is identical to a non-partitioned table; no modifications are necessary when accessing a partitioned table using SQL queries and DML statements. Partitioning Key ======================== Each row in a partitioned table is unambiguously assigned to a single partition. The partitioning key is comprised of one or more columns that determine the partition where each row will be stored. Oracle automatically directs insert, update, and delete operations to the appropriate partition through the use of the partitioning key. When to Partition a Table ========================== Here are some suggestions for when to partition a table: Tables greater than 2 GB should always be considered as candidates for partitioning. Tables containing historical data, in which new data is added into the newest partition. A typical example is a historical table where only the current month's data is updatable and the other 11 months are read only. When the contents of a table need to be distributed across different types of storage devices. When to Partition an Index ============================= Here are some suggestions for when to consider partitioning an index: Avoid rebuilding the entire index when data is removed. Perform maintenance on parts of the data without invalidating the entire index. Reduce the impact of index skew caused by an index on a column with a monotonically increasing value. Partitioned Index-Organized Tables =================================== Partitioned index-organized tables are very useful for providing improved performance, manageability, and availability for index-organized tables. For partitioning an index-organized table: ============================================ Partition columns must be a subset of the primary key columns Secondary indexes can be partitioned (both locally and globally) OVERFLOW data segments are always equi-partitioned with the table partitions See Also: Oracle Database Concepts for more information about index-organized tables System Partitioning System partitioning enables application-controlled partitioning without having the database controlling the data placement. The database simply provides the ability to break down a table into partitions without knowing what the individual partitions are going to be used for. All aspects of partitioning have to be controlled by the application. For example, an insertion into a system partitioned table without the explicit specification of a partition will fail. System partitioning provides the well-known benefits of partitioning (scalability, availability, and manageability), but the partitioning and actual data placement are controlled by the application. See Also: Oracle Database Data Cartridge Developer's Guide for more information about system partitioning Partitioning for Information Lifecycle Management Information Lifecycle Management (ILM) is concerned with managing data during its lifetime. Partitioning plays a key role in ILM because it enables groups of data (that is, partitions) to be distributed across different types of storage devices and managed individually.
Views: 6873 OnLinE ReSoUrCe
Oracle Virtual Column
 
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Oracle Virtual Column https://easy-learning-tech.blogspot.in/2018/05/virtual-column-in-oracle.html
Views: 36 Siva Academy
Oracle Virtual Column vs pseudo column
 
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Oracle Virtual Column vs pseudo column Details on pseudo column @ https://youtu.be/GIGmZwShGh4 Details on Virtual Column @ https://youtu.be/qUALFDzLDJw
Views: 29 Siva Academy
Data Warehouse 9 ColumnStore Indexes
 
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02:27 Row storage 05:40 ColumnStore Storage 12:32 ColumnStore Batch Mode and CPU caches 18:11 Demo ColumnStore Index Segment Elimination 31:28 Clustered Columstore Index Delta Store SQL Server 2012 Non-Clustered Columnstore Index, SQL Server 2014 Clustered Columnstore Index Brain Mitchell: What's New for Columnstore Indexes and Batch Mode Processing http://channel9.msdn.com/Events/TechEd/NorthAmerica/2013/DBI-B322#fbid=GMKVwjUCe2g
Views: 7467 Garrett Edmondson
Oracle tutorial : What is Virtual column in Oracle PL SQL
 
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This video will show you " Oracle tutorial: What is Virtual column in Oracle PL SQL " sql calculated field computed column oracle-11g-new-feature-virtual-column Oracle tutorial : What is Virtual column in oracle Syntax : column_name [datatype] [GENERATED ALWAYS] AS [expression] [VIRTUAL] 1)The values of the virtual column are not stored in the database. 2)You can not update the values of virtual column. 3)when you try to modify it will give oracle error. 4)These are read only values. 5)Virtual columns used in the WHERE clause of UPDATE and DELETE statement 6)Constraints can be created on them. #techquerypond https://techquerypond.wordpress.com https://twitter.com/techquerypond
Views: 1376 Tech Query Pond
How to use Pivot and Unpivot? (how to change rows to column and column to rows)
 
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This is a video tutorial on using pivot and unpivot operators to change rows to column and columns to rows when needed, the video also demonstrates a way to change from rows to column without using the pivot operator which can be helpful if you are using and older version of oracle or some other database without the feature of pivot and unpivot. Both the operators are explained with an example for better understanding
Views: 6823 Kishan Mashru
How to create Virtual Columns in Oracle Database
 
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How to create Virtual Columns in Oracle Database 12c When queried, virtual columns appear to be normal table columns, but their values are derived rather than being stored on disc. The syntax for defining a virtual column is listed below. column_name [datatype] [GENERATED ALWAYS] AS (expression) [VIRTUAL] If the datatype is omitted, it is determined based on the result of the expression. The GENERATED ALWAYS and VIRTUAL keywords are provided for clarity only. The script below creates and populates an employees table with two levels of commission. It includes two virtual columns to display the commission-based salary. The first uses the most abbreviated syntax while the second uses the most verbose form. CREATE TABLE employees ( id NUMBER, first_name VARCHAR2(10), last_name VARCHAR2(10), salary NUMBER(9,2), comm1 NUMBER(3), comm2 NUMBER(3), salary1 AS (ROUND(salary*(1+comm1/100),2)), salary2 NUMBER GENERATED ALWAYS AS (ROUND(salary*(1+comm2/100),2)) VIRTUAL, CONSTRAINT employees_pk PRIMARY KEY (id) ); INSERT INTO employees (id, first_name, last_name, salary, comm1, comm2) VALUES (1, 'JOHN', 'DOE', 100, 5, 10); INSERT INTO employees (id, first_name, last_name, salary, comm1, comm2) VALUES (2, 'JAYNE', 'DOE', 200, 10, 20); COMMIT; Querying the table shows the inserted data plus the derived commission-based salaries. SELECT * FROM employees; ID FIRST_NAME LAST_NAME SALARY COMM1 COMM2 SALARY1 SALARY2 ---------- ---------- ---------- ---------- ---------- ---------- ---------- ---------- 1 JOHN DOE 100 5 10 105 110 2 JAYNE DOE 200 10 20 220 240 2 rows selected. SQL The expression used to generate the virtual column is listed in the DATA_DEFAULT column of the [DBA|ALL|USER]_TAB_COLUMNS views. COLUMN data_default FORMAT A50 SELECT column_name, data_default FROM user_tab_columns WHERE table_name = 'EMPLOYEES'; COLUMN_NAME DATA_DEFAULT ------------------------------ -------------------------------------------------- ID FIRST_NAME LAST_NAME SALARY COMM1 COMM2 SALARY1 ROUND("SALARY"*(1+"COMM1"/100),2) SALARY2 ROUND("SALARY"*(1+"COMM2"/100),2) 8 rows selected. SQL Notes and restrictions on virtual columns include: 1)Indexes defined against virtual columns are equivalent to function-based indexes. 2)Virtual columns can be referenced in the WHERE clause of updates and deletes, but they cannot be manipulated by DML. 3)Tables containing virtual columns can still be eligible for result caching. 4)Functions in expressions must be deterministic at the time of table creation, but can subsequently be recompiled and made non-deterministic without invalidating the virtual column. In such cases the following steps must be taken after the function is recompiled: a)Constraint on the virtual column must be disabled and re-enabled. b)Indexes on the virtual column must be rebuilt. c)Materialized views that access the virtual column must be fully refreshed. d)The result cache must be flushed if cached queries have accessed the virtual column. e)Table statistics must be regathered. 5)Virtual columns are not supported for index-organized, external, object, cluster, or temporary tables. 6)The expression used in the virtual column definition has the following restrictions: a.It cannot refer to another virtual column by name. b.It can only refer to columns defined in the same table. c.If it refers to a deterministic user-defined function, it cannot be used as a partitioning key column. e.The output of the expression must be a scalar value. It cannot return an Oracle supplied datatype, a user-defined type, or LOB or LONG RAW.
Views: 442 OracleDBA
How To Add New Column(Field) in Existing table Using Oracle Database
 
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In this video You will learn how to Add new column after creating a new table or existing tables in oracle database , This video help us adding one or more than columns as per project requirement. add a column add a column in a table add a column in sql add a column in table add a column sql add a column to a table add a column to an existing table add a column to sql table add a column to table add a new column add column add column alter table add column in a table add column in a table oracle add column in existing table add column in oracle add column in sql add column in table add column in table oracle add column in table sql add column into table add column ms sql add column oracle add column oracle sql add column oracle table add column pl sql add column sql add column sql oracle add column sql script add column sql server add column sql server 2008 add column sql server 2012 add column table add column table oracle add column to a table add column to a table sql add column to database add column to existing table add column to existing table sql server add column to oracle table add column to sql add column to sql server table add column to sql table add column to table add column to table oracle add column to table sql add column to table sql server add column to table sql server 2008 add column tsql add field sql add field sql server add field to table sql add new column add new column in existing table add new column in oracle database tables add new column in table sql add new column sql add new column to sql table add new column to table add new column to table oracle add new column to table sql add sql column add table column add to table sql alter a table sql alter table alter column sql alter table change column sql alter table column sql alter table command sql table add column sql table alter sql update table add column sql update table column sqlplus alter table table add column table alter table columns add update add column update column oracle update table add column update table add column oracle update table add column sql
Views: 2438 Programming Lifestyle
Reorganizing Tables in Oracle
 
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The clip explains why reorganizing of tables may or may not be required and how to do it. Text version is here: https://uhesse.com/2010/08/23/reorganizing-tables-in-oracle-is-it-worth-the-effort/
Indexing JSON Data in Oracle Database 12c
 
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This video gives an overview of indexing JSON data in Oracle database 12c. For more information see: https://oracle-base.com/articles/12c/indexing-json-data-in-oracle-database-12cr1 Website: https://oracle-base.com Blog: https://oracle-base.com/blog Twitter: https://twitter.com/oraclebase Cameo by Bertrand Drouvot : Blog: https://bdrouvot.wordpress.com/ Twitter : https://twitter.com/BertrandDrouvot Cameo appearances are for fun, not an endorsement of the content of this video. All trademarks, product names and logos are the property of their respective owners.
Views: 1649 ORACLE-BASE.com
How Many Indexes Are Too Many?: Finding All The Red Sweets Part 5
 
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Every index you add to a table increases its storage requirements and DML overheads. So it's a good idea to create as few as possible. When you have two or more indexes using the same columns, you may be able to get away with just one. But how do you decide which to keep? This video discusses how to analyze your queries so you can cut the number of indexes you create. ============================ The Magic of SQL with Chris Saxon Copyright © 2015 Oracle and/or its affiliates. Oracle is a registered trademark of Oracle and/or its affiliates. All rights reserved. Other names may be registered trademarks of their respective owners. Oracle disclaims any warranties or representations as to the accuracy or completeness of this recording, demonstration, and/or written materials (the “Materials”). The Materials are provided “as is” without any warranty of any kind, either express or implied, including without limitation warranties or merchantability, fitness for a particular purpose, and non-infringement.
Views: 2167 The Magic of SQL
Difference Between Row Level Storage(Oracle) and Column Level Storage (Vertica)
 
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With changing Needs New technologies are coming in market even the ways to store data is changing, The video gives a very high level overview of the differences btw Columnar and Row Based storage database
Views: 6379 Tech Coach
PIVOT Tutorial - generating dynamic column with PIVOT Interview Question SQL
 
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In this lecture you will learn about PIVOT operator and using it to generate dynamic columns.PIVOT is very use full operator to convert values into columns. PIVOT: •Convert your output from (values)vertical order to horizontal(making columns) one Topic to cover: •PIVOT example •PIVOT syntax •Interview Question •PIVOT on northwind •Dynamic PIVOT query http://www.techsapphire.in/index/pivot_sql_lesson_with_generating_dynamic_columns_with_pivot/0-158
Views: 28147 techsapphire
mysql tutorial for beginners (6/8) : Indexes
 
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mysql tutorial for beginners (6/8) : Indexes As things stand, the table students works and can be searched without problem by MySQL—until it grows to more than a couple of hundred rows, At that point, database accesses will get slower and slower with every new row added, because MySQL has to search through every row whenever a query is issued. This is like searching through every book in a library whenever you need to look something up. Of course, you don’t have to search libraries that way, because they have either a card index system or, most likely, a database of their own. The way to achieve fast searches is to add an index, either when creating a table or at any time afterward. But the decision is not so simple. For example, there are different index types such as a regular INDEX, PRIMARY KEY, and FULLTEXT. Also, you must decide which columns require an index, a judgment that requires you to predict whether you will be searching any of the data in that column. And even when you’ve decided that, you still have the option of reducing index size by limiting the amount of each column to be indexed. If we imagine the searches that may be made on the students table, it becomes apparent that all of the columns may need to be searched. Anyway, go ahead and add an index to each of the columns, using the commands: ALTER TABLE students ADD INDEX(name(3)); An alternative to using ALTER TABLE to add an index is to use the CREATE INDEX command. They are equivalent, except that CREATE INDEX cannot be used for creating a PRIMARY KEY CREATE INDEX surname ON students (surname(5)); DESCRIBE students; These commands create indexes on both the name and surname columns, limiting name index to only the first 3 characters, and surname index to the first 5 characters. For instance, when MySQL indexes the following name: SAFAA It will actually store in the index only the first 3 characters: SAF This is done to minimize the size of the index, and to optimize database access speed. DESCRIBE command shows the key MUL for each column. This key means that multiple occurrences of a value may occur within that column, which is exactly what we want, as name or surname may appear many times. You don’t have to wait, until after creating a table to add indexes. In fact, doing so can be time-consuming, as adding an index to a large table can take a very long time. Therefore, let’s look at a command that creates the table students with indexes already in place. CREATE TABLE students ( Id_studnet SMALLINT UNSIGNED NOT NULL AUTO_INCREMENT, name VARCHAR(10) NOT NULL, surname VARCHAR(20) NOT NULL, email VARCHAR(30) NOT NULL, INDEX(name(3)), INDEX(surname(5)), ,PRIMARY KEY(id_studnet),UNIQUE(email)); Another important index, PK, its single unique key for each student to enable instant accessing of a row. The importance of having a key with a unique value for each row will come up when we start to combine data from different tables. You can add PK, while you create the table at the first time, or later by issuing the following command: ALTER TABLE students ADD PRIMARY KEY(id_student); The last important index, FULLTEXT index Unlike a regular index, MySQL’s FULLTEXT allows super-fast searches of entire columns of text. It stores every word in every data string in a special index that you can search using “natural language,” in a similar manner to using a search engine. It’s not strictly true that MySQL stores all the words in a FULLTEXT index, because it has a built-in list of more than 500 words that it chooses to ignore because they are so common that they aren’t very helpful for searching anyway. This list, called stopwords, includes the, as, is, of, and so on. The list helps MySQL run much more quickly when performing a FULLTEXT search and keeps database sizes down. FULLTEXT indexes can be created for CHAR, VARCHAR, and TEXT columns only. A FULLTEXT index definition can be given in the CREATE TABLE statement when a table is created, or added later using ALTER TABLE (or CREATE INDEX). Adding a FULLTEXT index to the table students for the columns name and surname ALTER TABLE classics ADD FULLTEXT(name,surname); this index is in addition to the ones already created and does not affect them You can now perform FULLTEXT searches across this pair of columns. If you find that MySQL is running slower than you think it should be when accessing your database, the problem is usually related to your indexes. Either you don’t have an index where you need one, or the indexes are not optimally designed. Tweaking a table’s indexes will often solve such a problem. In the next tutorial, we will learn about, using FOREIGN KEY Constraints and how to join tables together. Subscribe for more: ---------------------------------------------------------------------------- https://www.youtube.com/subscription_center?add_user=saf3al2a SWE.Safaa Al-Hayali - saf3al2a
Views: 26305 Safaa Al-Hayali
Clustered vs. Nonclustered Index Structures in SQL Server
 
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Clustered and nonclustered indexes share many of the same internal structures, but they're fundamentally different in nature. Watch Microsoft Certified IT Professional Jon Seigel explain the similarities and differences of clustered and nonclustered indexes, using a real-world example to show how these structures work to improve the performance of SQL queries. Blog post on primary key vs. the clustered index: http://voluntarydba.com/post/2012/10/02/The-Primary-Key-vs-The-Clustered-Index.aspx CREATE INDEX statement reference: http://technet.microsoft.com/en-us/library/ms188783.aspx ALTER INDEX statement reference: http://technet.microsoft.com/en-us/library/ms188388.aspx Index navigation internals by example: http://sqlblog.com/blogs/paul_white/archive/2011/08/09/sql-server-seeks-and-binary-search.aspx Sample index data is from the AdventureWorksLT2008R2 sample database: http://awlt2008dbscript.codeplex.com/releases/view/46169 Visit my channel for more database administration videos: https://www.youtube.com/voluntarydba Subscribe to get notified about my latest videos: https://www.youtube.com/voluntarydba?sub_confirmation=1 Read additional content on my blog: http://voluntarydba.com Follow on Twitter: https://twitter.com/voluntarydba Like on Facebook: https://facebook.com/voluntarydba
Views: 283299 Voluntary DBA
Oracle SQL Tutorial 14 - Column-Level and Table-Level Constraints
 
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In the previous video we talked about adding constraints at the column-level. We made it nice and simple by only requiring a few keywords, but the problem we were having is that we could not assign a name to the constraint, which many people like to do so we can reference easily if we need to at a later time. To do this, it requires a little bit more typing, but it will give us extra flexibility and many consider it to be the higher quality approach to adding constraints. Let's go though a simple example. Let's say we have a users table with a user_id column that we want to make a primary key. We will create the table like this: CREATE TABLE( user_ id NUMBER PRIMARY KEY ) Instead of adding the PRIMARY KEY keywords after the data type, we add: CONSTRAINT user_pk PRIMARY KEY Now, we have assigned the name user_pk to this constraint. You can do the same with other constraints, such as UNIQUE. The syntax would be CONSTRAINT username_un UNIQUE. The other way to create constraints requires to put all of our constraints at the bottom of our table creation rather than inline with the column. This type of constraint is known as a table-level constraints. To make a column a primary key using table-level constraints, we add it to the CREATE TABLE command as if it is another row and use the CONSTRAINT keyword to tell Oracle that what is coming is a constraint, not a column in our table. CREATE TABLE users( user_id NUMBER, username VARCHAR2(50 CHAR), CONSTRAINT username_un UNIQUE (username), CONSTRAINT users_pk PRIMARY KEY (user_id) ) The primary differences here is that you have to put the column you are talking about in parenthesis after the PRIMARY KEY keyword. That's because it's at the end of the table and you need a way to tell it what column you are talking about. The option of putting it at the end of the table has the added benefit in this situation because if we needed to have a primary key that is the combination of multiple columns, we can do that by just adding the other column in the PRIMARY KEY parenthesis right after a comma. In summary, there are three ways to make constraints. The first is at the column level, unnamed. The second is at the column level, named. The third is at the table level, also named. In the next video we are going to create a named constraint in Oracle SQL Developer, so stay tuned and be sure to subscribe! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Support me! http://www.patreon.com/calebcurry Subscribe to my newsletter: http://bit.ly/JoinCCNewsletter Donate!: http://bit.ly/DonateCTVM2. ~~~~~~~~~~~~~~~Additional Links~~~~~~~~~~~~~~~ More content: http://CalebCurry.com Facebook: http://www.facebook.com/CalebTheVideoMaker Google+: https://plus.google.com/+CalebTheVideoMaker2 Twitter: http://twitter.com/calebCurry Amazing Web Hosting - http://bit.ly/ccbluehost (The best web hosting for a cheap price!)
Views: 14069 Caleb Curry
Oracle Pseudo columns
 
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pseudo columns in oracle
Views: 78 Siva Academy
How to use the Oracle SQL PIVOT Clause
 
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PIVOT allows you to "flip a table on its side", i.e. Columns to Rows / Rows to Columns. Previously we did this with DECODE or CASE. As of Oracle 11g, Oracle Database includes the PIVOT clause (and UNPIVOT). Oracle expert Geoff Wiland from SkillBuilders will demonstrate PIVOT, UNPIVOT, including the use of aggregate functions.
Views: 10111 SkillBuilders
55. ALTER TABLE to Modify existing column in PL/SQL Oracle
 
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In this video you will learn about ALTER TABLE to Modify existing column in PL/SQL Oracle. For Support =========== Email: [email protected] Contact Form: http://www.learninhindi.com/home/contact Our Social Media ================ Facebook: https://www.facebook.com/LearnInHindi Twitter: https://twitter.com/LearnInHindi For Training & Videos ===================== For more videos and articles visit: http://www.learninhindi.com Free Java Programming In Hindi Course ===================================== https://www.youtube.com/playlist?list=PLOZ3jentlCDAwwhMyoLISrxkXTADGp7PH Free Oracle PL/SQL Programming In Hindi Course ============================================== https://www.youtube.com/playlist?list=PLB5DA82419C2D99B6 Free C Programming In Hindi Course ================================== https://www.youtube.com/playlist?list=PLOZ3jentlCDAxKpBLMWogxSdy6BZcsAJq Trips & Tricks Channel ====================== https://www.youtube.com/channel/UCGmLfkuCo-3lHHJXRJ9HUMw Programming in Hindi Channel ============================ https://www.youtube.com/channel/UCudElIDgwNrybeAvXIy1HZQ
Views: 3730 ITORIAN
Collections in Oracle PLSQL
 
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Complete Oracle PL/SQL Tutorial for Beginners Playlist here https://www.youtube.com/playlist?list=PLI5t0u6ye3FE_9SZcS0cQZDU2qn0uB1Oi ************************************************** Composite DataType - Collections in Oracle PL SQL 1. Difference Between Records and Collections 2. Types of Collections in Oracle 3. VARRAYS 4. Nested Table 3. Associative Arrays / Index BY Tables 4. Multi Dimensional Arrays Using Collections and Records
Views: 15755 yrrhelp
Oracle SQL Developer Tutorial For Beginners  94   Alias for Columns
 
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Oracle SQL Developer Tutorial For Beginners Series. This course introduces Oracle SQL Development for its subscribers. Currently this is based on Oracle 12c. The test environment is in Windows 10.
Views: 571 Sam Dhanasekaran
SQL: Indexes - Bit Map & B-trees
 
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In this tutorial, you'll learn when to use b-tree and bitmap index
Views: 52962 radhikaravikumar
Oracle Database 12c demos: In-Memory Column Store Architecture Overview
 
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The demonstration provides an overview of the architecture of the In-Memory Column Store feature introduced in Oracle Database 12c Release 1 patchset 1.
Get Table Names with Column Names and Data Types in SQL Server - SQL Server Tutorial
 
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In this video ,we will generate the script that will return us all the table names with column names and data type of those columns. We often need this information. Let's say we are going to prepare mapping document for load the data from Source Database to Destination database. We can get the list of all tables with column names and data types from Source Database and Destination Database and then paste in Excel and map the required input columns to output columns for ETL Process. Blog link with scripts used in video http://sqlage.blogspot.com/2015/02/get-all-tables-with-column-names-and.html
Views: 44629 TechBrothersIT
Clustered and nonclustered indexes in sql server   Part 36
 
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In this video we will learn about 1. Different types of indexes in sql server 2. What are clustered indexes 3. What are NonClustered indexes 4. Difference between clustered and non clustered indexes Text version of the video http://csharp-video-tutorials.blogspot.co.uk/2012/09/clustered-and-non-clustered-indexes.html Slides http://csharp-video-tutorials.blogspot.com/2013/09/part-36-clustered-nonclustered-indexes.html All SQL Server Text Articles http://csharp-video-tutorials.blogspot.com/p/free-sql-server-video-tutorials-for.html All SQL Server Slides http://csharp-video-tutorials.blogspot.com/p/sql-server.html All Dot Net and SQL Server Tutorials in English https://www.youtube.com/user/kudvenkat/playlists?view=1&sort=dd All Dot Net and SQL Server Tutorials in Arabic https://www.youtube.com/c/KudvenkatArabic/playlists
Views: 450174 kudvenkat
Oracle Database 12c demos: In-Memory Column Store Compression
 
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The demonstration illustrates how inmemory compression of inmemory objects populated in the IM column store can influence either query performance or storage savings in IM column store.
Oracle SQL Tutorial   Adding a column to a table   YouTube
 
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Oracle SQL Tutorial Adding a column to a table how to add column in your oracle table is shown in above tutorial
Views: 175 magan lal
Oracle Video Tutorial In Telugu Pseudo Columns Part 19
 
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Oracle Video Tutorial In Telugu hafiztime hafiz telugu videos #telugutechtuts #hafiztime -~-~~-~~~-~~-~- Please watch: "ఈ మొబైల్స్ కొనకండి | మీ డబ్బులు కాపాడుకోండి" https://www.youtube.com/watch?v=m6IBjIZFxcY -~-~~-~~~-~~-~-
Views: 1744 Telugu TechTuts

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