General MySQL Oracle SQL Server

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Using Subqueries with the IN Operator in MySQL
How To Use Subqueries with the IN Operator in MySQL? A subquery can be used with the IN operator as "expression IN (subquery)". The subquery should return a single column with one or more rows to form a list of values to be used by the IN operation. The following tutorial exercise shows you how to u... 2017-09-17, 3142🔥, 0💬

Add a New Column to an Existing Table in MySQL
How To Add a New Column to an Existing Table in MySQL? If you have an existing table with existing data rows, and want to add a new column to that table, you can use the "ALTER TABLE ... ADD COLUMN" statement. The tutorial script below shows you a good example: mysql&gt; ALTER TABLE tip ADD COLU... 2018-03-04, 3135🔥, 0💬

Starting mysqld to Support BDB Storage Engine in MySQL
How To Start mysqld to Support the BDB Storage Engine in MySQL? The default "mysqld" program does not support the BDB storage engine. If you want to use the BDB storage engine, you can start MySQL server with the "mysqld-max" program. The tutorial exercise below shows you how to start "mysqld-max" a... 2017-08-13, 3135🔥, 0💬

Dump a Table to a File with "mysqldump" Command in MySQL
How To Dump a Table to a File with "mysqldump" in MySQL? If you want to dump all rows in a table from the server to a file, you can use "mysqldump" with the "-f fileName" option as show in the following tutorial exercise: &gt;cd \mysql\bin &gt;mysqldump -u root -r \temp\links.txt test links ... 2018-05-19, 3133🔥, 0💬

Data File for InnoDB Storage Engine in MySQL
Where Table Data Is Stored by the InnoDB Storage Engine in MySQL? By default, MySQL provides \mysql\data directory for all storage engines to store table data. Under \mysql\data directory, InnoDB storage engine will create 3 files to store and manage all tables that use the InnoDB storage engine: ib... 2017-08-13, 3133🔥, 0💬

Creating New Tables with SELECT Statements in MySQL
How To Create a New Table by Selecting Rows from Another Table in MySQL? Let's say you have a table with many data rows, now you want to create a backup copy of this table of all rows or a subset of them, you can use the "CREATE TABLE ... SELECT" statement. The tutorial script below gives you a good... 2018-03-04, 3130🔥, 0💬

Tables Using MyISAM Storage Engine in MySQL
How To Create a New Table Using MyISAM Storage Engine in MySQL? MyISAM storage engine is based on the ISAM (Indexed Sequential Access Method) concept, which was first developed at IBM to store and retrieve data on secondary storage systems like tapes. MyISAM storage engine offers fast data storage a... 2017-09-12, 3125🔥, 0💬

What Is a Dead Lock in MySQL
What Is a Dead Lock in MySQL? A dead lock is phenomenon happens between two transactions with each of them holding a lock that blocks the other transaction as shown in the following diagram: (transaction 1) (transaction 2) update row X to create lock 1 update row Y to create lock 2 update row X (blo... 2017-04-28, 3125🔥, 0💬

What Is a Subquery in MySQL
What Is a Subquery in MySQL? A subquery is a SELECT statement used as part of the selection criteria of the main SELECT statement. The subquery specified in the WHERE clause will be evaluated repeated on each row of the selection base table. The output of the subquery will be used in the final evalu... 2017-09-17, 3118🔥, 0💬

Read Consistency Support in MySQL in MySQL
How Does MySQL Handle Read Consistency in MySQL? Read consistency is a concept that describes how consistent the output will be on two subsequent read operations. A read operation is usually a stand alone SELECT statement or a SELECT subquery in a parent statement. A database server can support up t... 2017-08-03, 3115🔥, 0💬

Repair MyISAM Tables in MySQL
How To Check and Repair MyISAM Tables in MySQL? If you have a corrupted MyISAM table, like the one resulted from the previous tutorial exercise, you can use the "CHECK TABLE" and "REPAIR TABLE" commands to try to repair it. The following tutorial exercise gives you a good example of repairing a corr... 2017-09-01, 3113🔥, 0💬

Inner Join with the WHERE Clause in MySQL
How To Write an Inner Join with the WHERE Clause in MySQL? If you don't want to use the INNER JOIN ... ON clause to write an inner join, you can put the join condition in the WHERE clause as shown in the following query example: mysql&gt; SELECT l.id, l.url, r.comment FROM fyi_links l, fyi_rates... 2017-09-28, 3112🔥, 0💬

Use Existing Column Values in the SET Clause in MySQL
How To Use Existing Column Values in the SET Clause in MySQL? If a row matches the WHERE clause in a UPDATE statement, existing values in this row can be used in expressions to provide new values in the SET clause. Existing values are represented by column names in the expressions. The tutorial exer... 2018-01-13, 3106🔥, 0💬

What Are DDL Statements in MySQL
What Are DDL Statements in MySQL? DDL (Data Definition Language) statements are statements to create and manage data objects in the database. The are 3 primary DDL statements: CREATE - Creating a new database object. ALTER - Altering the definition of an existing data object. DROP - Dropping an exis... 2018-03-10, 3102🔥, 0💬

Deleting an Existing Database in MySQL
How To Drop an Existing Database in MySQL? If want to drop an existing database from the MySQL server, you can use the DROP DATABASE statement. Here is a good example of dropping an existing database: $con = mysql_connect('localhost:8888' ,'dev', 'iyf'); $sql = 'DROP DATABASE fyi'; if (mysql_query($... 2017-10-23, 3100🔥, 0💬

Giving Privileges at Server Level in MySQL
How To Grant User Privileges at the Global Level in MySQL? If you want to grant a user privilege at the global level, you can use the "GRANT privilegeName ON *.* TO userName" command. The argument "*.*" in the command stands for all database and all tables. The following tutorial exercise shows you ... 2017-08-21, 3100🔥, 0💬

Order of Columns in the SET Clause in MySQL
Is the Order of Columns in the SET Clause Important in MySQL? Yes. The order of columns in the SET clause of the UPDATE statement is important. There is a BIG DIFFERENCE between MySQL and Oracle on update columns with previous values: Oracle provides you the existing values from the database on colu... 2018-01-13, 3099🔥, 0💬

Deleting an Existing Row from a Table in MySQL
How To Delete an Existing Row from a Table in MySQL? If you want to delete an existing row from a table, you can use the DELETE statement with a WHERE clause to identify that row. Here is good sample of DELETE statements: mysql&gt; INSERT INTO fyi_links (url, id) VALUES ('www.myspace.com', 301);... 2018-01-08, 3099🔥, 0💬

Failed to Create a Database in MySQL
What Happens If You Do Not Have Privileges to Create Database in MySQL? If your MySQL server is provided by your Internet service company, your user account will most likely have no privilege to create new databases on the server. In that case, your CREATE DATABASE statement will fail. Here is an ex... 2017-11-11, 3098🔥, 0💬

What are Date and Time Data Types in MySQL
What Are Date and Time Data Types in MySQL? MySQL supports the following date and time data types: DATE - A date in the range of '1000-01-01' and '9999-12-31'. Default DATE format is "YYYY-MM-DD". DATETIME - A date with the time of day in the range of '1000-01-01 00:00:00' and '9999-12-31 23:59:59'.... 2018-03-24, 3091🔥, 0💬

Drop an Existing View in MySQL
How To Drop an Existing View in MySQL? If you have an existing view, and you don't want it anymore, you can delete it by using the "DROP VIEW viewName" statement as shown in the following script: mysql&gt; DROP VIEW faqComment; Query OK, 0 rows affected (0.00 sec) mysql&gt; SELECT * FROM faq... 2018-01-24, 3088🔥, 0💬

Viewing User Privileges in MySQL
How To View User Privileges in MySQL? If a regular user wants to see his/her own granted privileges, he/she can use the "SHOW GRANTS" command. If the "root" user wants to see other user's granted privileges, he/she can use the "SHOW GRANTS FOR userName" command. The following tutorial exercise shows... 2017-08-21, 3086🔥, 0💬

MySQL Functions for Miscellaneous Purposes
Where to find reference information and tutorials on MySQL database functions for Miscellaneous Purposes? I want to know how to use CAST(), SLEEP() and other miscellaneous functions. Here is a collection of reference information and tutorials on MySQL database functions for Miscellaneous Purposes co... 2026-03-22, 3083🔥, 0💬

Ways to End the Current Transaction in MySQL
How To End the Current Transaction in MySQL? There are several ways the current transaction can be ended implicitly or explicitly: In "Autocommit On" mode, a single-statement transaction will be ended implicitly when the execution of the statement ends. Changes will be committed. Running the COMMIT ... 2016-10-17, 3082🔥, 0💬

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General MySQL Oracle SQL Server