General MySQL Oracle SQL Server

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What Is RollBack in MySQL
What Is Rollback in MySQL? Rollback is a way to terminate a transaction with all database changes not saving to the database server.   ⇒ MySQL Database Tutorials ⇐ What Is Commit in MySQL ⇑ Database Basics and Terminologies in MySQL ⇑⇑ MySQL Database Tutorials 2016-10-16, 3115🔥, 0💬

Analyze Tables with "mysqlcheck" Command in MySQL
How To Analyze Tables with "mysqlcheck" in MySQL? If you want analyze tables with "mysqlcheck", you need to use the "--analyze" option. The following tutorial exercise shows you how to analyze all tables in "mysql" database: &gt;cd \mysql\bin &gt;mysqlcheck -u root --analyze mysql mysql.colu... 2018-02-28, 3113🔥, 0💬

What Is SQL Standard in Oracle
What Is SQL Standard in Oracle? SQL, SEQUEL (Structured English Query Language), is a language for RDBMS (Relational Database Management Systems). SQL was developed by IBM Corporation. SQL became an ANSI standard, called SQL-87, in 1986. ISO made a major revision, called SQL-92, in 1992. The latest ... 2020-05-29, 3110🔥, 0💬

Help at the SQL Prompt in Oracle
How To Get Help at the SQL Prompt in Oracle? Once SQL*Plus is started, you will get a SQL prompt like this: SQL&gt;. This where you can enter commands for SQL*Plus to run. To get help information at the SQL prompt, you can use the HELP command as shown in the following tutorial example: SQL&... 2020-08-25, 3109🔥, 0💬

Show Dropped Tables in Recycle Bin in Oracle
How To View the Dropped Tables in Your Recycle Bin in Oracle? You can look what's in your recycle bin through the predefined view called RECYCLEBIN. You can use the SELECT statement to list the dropped tables as shown in the following script: SQL&gt; connect HR/fyicenter Connected. SQL&gt; C... 2019-05-14, 3100🔥, 0💬

"ALTER INDEX ... REORGANIZE" - Defragmenting Indexes in SQL Server
How To Defragment Indexes with ALTER INDEX ... REORGANIZE in SQL Server? When an index is defragmented to a small percentage, like &lt; 30%, you can use the "ALTER INDEX ... REORGANIZE" statement to defragment the index. Here is a tutorial exercise on defragmenting indexes: USE FyiCenterData; GO... 2016-11-08, 3100🔥, 0💬

ONLINE/OFFLINE - Database States in SQL Server
What are database states in SQL Server? A database is always in one specific state. For example, these states include ONLINE, OFFLINE, or SUSPECT. To verify the current state of a database, select the state_desc column in the sys.databases catalog view. The following table defines the database state... 2016-11-20, 3099🔥, 0💬

"sp_help" - Getting a List of Columns in a View in SQL Server
How To Get a List of Columns in a View using the "sp_help" Stored Procedure in SQL Server? Another way to get a list of columns from a view is to use the "sp_help" stored procedure. "sp_help" returns more than just a list of columns. It returns: the view information, the column information, the iden... 2016-11-05, 3098🔥, 0💬

DML (Data Manipulation Language_Statements in SQL Server
What Are DML (Data Manipulation Language) Statements in SQL Server? DML (Data Manipulation Language) statements are statements to change data values in database tables. The are 3 primary DML statements: INSERT - Inserting new rows into database tables. For example "INSERT INTO fyi_links VALUES (101,... 2016-11-03, 3097🔥, 0💬

Use SYS Account to Connect to the Server in Oracle
How To Connect to the Server with User Account: SYS in Oracle? SYS is a very special user account. It has been associated with the highest privilege call SYSDBA. Normally, you should not connect to the server with SYS. But if you want to use it, you need to use a special connect command: &gt;cd ... 2019-07-21, 3095🔥, 0💬

Dropped Tables with Indexes in Oracle
What Happens to Indexes If You Drop a Table in Oracle? If you drop a table, what happens to its indexes? The answer is that if a table is dropped, all its indexes will be dropped too. Try the following script to see yourself: CREATE TABLE student (id NUMBER(5) PRIMARY KEY, first_name VARCHAR(80) NOT... 2019-04-22, 3092🔥, 0💬

"DROP USER" - Deleting a Database User in SQL Server
How To Delete an Existing Database User in SQL Server? If you don't want to keep a database user any more, you should delete the user by using the "DROP USER" statement. This tutorial exercise shows how to delete "Dba_User": -- Login with "sa" USE FyiCenterData; GO DROP USER Dba_User; GO -- List all... 2022-01-24, 3089🔥, 0💬

What Is a READ WRITE Transaction in Oracle
What Is a READ WRITE Transaction in Oracle? A READ WRITE transaction is a transaction in which the read consistency is set at the statement level. In a READ WRITE transaction, a logical snapshot of the database is created at the beginning of the execution of each statement and released at the end of... 2019-08-23, 3088🔥, 0💬

Delete a Column in an Existing Table in Oracle
How To Delete a Column in an Existing Table in Oracle? If you have an existing column in a table and you need that column any more, you can delete it with ALTER TABLE ... DROP COLUMN statement. Here is an example SQL script: SQL&gt; CREATE TABLE emp_dept_90 2 AS SELECT * FROM employees WHERE dep... 2019-05-25, 3087🔥, 0💬

Using Group Functions in the SELECT Clause in MySQL
How To Use Group Functions in the SELECT Clause in MySQL? If group functions are used in the SELECT clause, they will be used on the rows that meet the query selection criteria, the output of group functions will be returned as output of the query. The following select statement returns 3 values cal... 2018-01-06, 3085🔥, 0💬

Variable Names Collide with Column Names in Oracle
What Happens If Variable Names Collide with Table/Column Names in Oracle? When a variable name collides with a column name, PL/SQL will use it as the variable if it is used where variable is allowed; It will be used as the column, if it is used where variable is not allowed but column is allowed. He... 2018-09-24, 3082🔥, 0💬

Managing Oracle Database Tables
Where to find answers to frequently asked questions on Managing Oracle Database Tables? Here is a list of frequently asked questions and their answers compiled by FYIcenter.com DBA team on Managing Oracle Database Tables. Clear answers are provided together with tutorial exercises to help beginners ... 2019-06-11, 3081🔥, 0💬

CONVERT/CAST Function in SQL Server Transact-SQL
How to convert value from one data type to another in SQL Server Transact-SQL? How to use the CONVERT function or the CAST function? In Transact-SQL, you can use CONVERT statements to convert values from one data type to another, in the syntax of: CONVERT(data_type, value[, style]) In this syntax, "... 2017-04-01, 3081🔥, 0💬

Define a Sub Function in Oracle
How To Define a Sub Function in Oracle? A sub function is a function defined and used inside another procedure or function. You need to define a sub function in the declaration part of the enclosing procedure or function. Sub function definition starts with the FUNCTION key word. Here is a sample sc... 2018-03-18, 3080🔥, 0💬

Working with Cursors in Oracle PL/SQL
Where to find answers to frequently asked questions on Working with Cursors in Oracle PL/SQL? Here is a list of frequently asked questions and their answers compiled by FYIcenter.com DBA team on Working with Cursors in Oracle PL/SQL. Clear answers are provided with tutorial exercises on defining, op... 2018-02-01, 3080🔥, 0💬

What Is Union in MySQL
What Is Union in MySQL? Join is data retrieval operation that combines multiple query outputs of the same structure into a single output.   ⇒ What Is ISAM in MySQL ⇐ What Is Join in MySQL ⇑ Database Basics and Terminologies in MySQL ⇑⇑ MySQL Database Tutorials 2017-07-07, 3080🔥, 0💬

Tables Using MEMORY Storage Engine in MySQL
How To Create a New Table Using the MEMORY Storage Engine in MySQL? MEMORY storage engine stores table data in computer system memory. This is good for creating temporary tables. MEMORY is not the default storage engine. You need to specify "ENGINE = MEMORY" at the end of the "CREATE TABLE" statemen... 2017-08-08, 3077🔥, 0💬

Show All Columns of an Existing Table in MySQL
How To Get a List of Columns in an Existing Table in MySQL? If you have an existing table, but you don't remember what are the columns used in the table, you can use the "SHOW COLUMNS FROM tableName" command to get a list of all columns of the specified table. You can also use the "DESCRIBE tableNam... 2018-03-10, 3074🔥, 0💬

Differences between NUMBER and BINARY_FLOAT in Oracle
What Are the Differences between NUMBER and BINARY_FLOAT in Oracle? The main differences between NUMBER and BINARY_FLOAT are: NUMBER stores values as fixed-point numbers using 1 to 22 bytes. BINARY_FLOAT stores values as single precision floating-point numbers.   ⇒ Differences between DATE and TIMES... 2020-04-25, 3070🔥, 0💬

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General MySQL Oracle SQL Server