General MySQL Oracle SQL Server

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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, 2653🔥, 0💬

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, 2653🔥, 0💬

Date-Only DATETIME Values in SQL Server Transact-SQL
What Happens If Date-Only Values Are Provided for DATETIME in SQL Server Transact-SQL? If only date value is provided in a DATETIME variable, the SQL Server will pad the time value with a zero, or '00:00:00.000', representing the midnight time of the day. The tutorial exercise below gives you some g... 2017-04-08, 2651🔥, 0💬

"DROP PROCEDURE" - Dropping an Existing Procedure in SQL Server
How To Drop an Existing Stored Procedure in SQL Server Transact-SQL? If you have an existing procedure that you don't want to use it anymore, you should delete it from the SQL Server by using the "DROP PROCEDURE" statement as shown in the tutorial example below: USE FyiCenterData; GO DROP PROCEDURE ... 2017-01-05, 2651🔥, 0💬

Defining and Using Table Alias Names in SQL Server
How To Define and Use Table Alias Names in SQL Server? When column names need to be prefixed with table names, you can define table alias name and use them to prefix column names. To define an alias for a table name, just enter the alias name right after the original table name in the FROM clause as... 2016-10-30, 2651🔥, 0💬

Example of Passing Parameters to Procedures in Oracle
How To Pass Parameters to Procedures in Oracle? Store procedures or functions can take parameters. You need to define parameters while defining the procedure, and providing values to parameters while calling the procedure. The script below shows you how to do this: SQL&gt; CREATE OR REPLACE PROC... 2019-03-08, 2650🔥, 0💬

Using SELECT Statements and GROUP BY Clauses in SQL Server
Where to find answers to frequently asked questions on Using SELECT Statements and GROUP BY Clauses in SQL Server? Here is a list of frequently asked questions and their answers compiled by FYIcenter.com DBA team on Using SELECT Statements and GROUP BY Clauses in SQL Server. Clear answers are provid... 2016-10-26, 2650🔥, 0💬

Export Data with Field Delimiters in Oracle
How To Export Data with a Field Delimiter in Oracle? The previous exercise allows you to export data with fixed field lengths. If you want export data with variable field lengths and field delimiters, you can concatenate your fields with an expression in the SELECT clause as shown in the tutorial ex... 2018-06-27, 2649🔥, 0💬

Simplest Tool to Run Commands on Oracle Server in Oracle
What Is the Simplest Tool to Run Commands on Oracle Servers in Oracle? The simplest tool to connect to an Oracle server and run commands to manage data is SQL*Plus. It is an Oracle database client tool that works as a command-line user interface to the database server. SQL*Plus allows you: Format, p... 2018-06-27, 2649🔥, 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, 2649🔥, 0💬

What Is Variable in SQL Server Transact-SQL
What is a variable in SQL Server Transact-SQL? A variable in Transact-SQL is a symbolic name representing a memory storage that holds a piece of data. A variable has the following the components: 1. Variable name - A symbolic name to represent the variable. Variable names in Transact-SQL must starts... 2017-04-22, 2649🔥, 0💬

Differences between Functions and Stored Procedures in SQL Server
What Are the Differences between User Defined Functions and Stored Procedures in SQL Server Transact-SQL? Differences between user defined functions and stored procedures are: Stored procedures does not return any data and they can not be used in expressions. User defined functions does return data ... 2016-12-24, 2649🔥, 0💬

Rename a Tablespace in Oracle
How To Rename a Tablespace in Oracle? You can easily rename a tablespace by using the ALTER TABLESPACE ... RENAME TO statement as shown in the example below: SQL&gt; CREATE TABLESPACE my_space 2 DATAFILE '/temp/my_space.dbf' SIZE 10M; Tablespace created. SQL&gt; ALTER TABLESPACE my_space REN... 2019-04-13, 2648🔥, 0💬

DECLARE Statements in SQL Server Transact-SQL
How to declare a variable in SQL Server Transact-SQL? How to use the DECLARE statements? In Transact-SQL, you must use DECLARE statements to declare variables. Declaring a variable is to define the variable name and the variable data type. In Transact-SQL, you can: Declare a single variable in a sin... 2017-04-04, 2648🔥, 0💬

Use "IN" Parameters in Oracle
How To Use "IN" Parameter Properly in Oracle? Here are the rules about IN parameters: A formal IN parameter acts like constant. It can not be assigned with new values. An actual IN parameter can take a value or a variable. An actual IN parameter is passed by reference to the specified value or the v... 2018-10-19, 2647🔥, 0💬

What Is Table in MySQL
What Is Table in MySQL? A table is a data storage structure with rows and columns.   ⇒ What Is Column in MySQL ⇐ What Is SQL in MySQL ⇑ Database Basics and Terminologies in MySQL ⇑⇑ MySQL Database Tutorials 2017-07-15, 2646🔥, 0💬

Experiment with Data Locks in MySQL
How To Experiment Data Locks in MySQL? If you want to have some experience with data locks, you can create two windows running two mysql transactions in two sessions. In session 1, you can run a UPDATE statement with REPEATABLE READ transaction isolation level to create an exclusive lock. Before com... 2017-04-28, 2646🔥, 0💬

Show Existing Locks on the Database in Oracle
How To View Existing Locks on the Database in Oracle? As can see from the pervious tutorial exercise, performance of the second session is greatly affected by the data lock created on the database. To maintain a good performance level for all sessions, you need to monitor the number of data locks on... 2019-08-08, 2643🔥, 0💬

Deleting All Rows in a Table in MySQL
How To Delete All Rows in a Table in MySQL? If you want to delete all rows from a table, you have two options: Use the DELETE statement with no WHERE clause. Use the TRUNCATE TABLE statement. The TRUNCATE statement is more efficient the DELETE statement. The tutorial exercise shows you a good exampl... 2018-01-08, 2643🔥, 0💬

What Is a Transaction in Oracle
What Is a Transaction in Oracle? A transaction is a logical unit of work requested by a user to be applied to the database objects. Oracle server introduces the transaction concept to allow users to group one or more SQL statements into a single transaction, so that the effects of all the SQL statem... 2019-09-16, 2642🔥, 0💬

Types of Cursors Supported in PL/SQL in Oracle
How Many Types of Cursors Supported in PL/SQL in Oracle? PL/SQL supports two types of cursors: The implicit cursor - A single default cursor that automatically connects to the last DML statement executed. Explicit cursors - User defined cursors with specific DML statements and execution statuses.   ... 2018-02-01, 2642🔥, 0💬

Update a Table Row with a RECORD in Oracle
How To Update a Table Row with a RECORD in Oracle? If you have a RECORD variable with data fields matching a table structure, you can update a row in this table with this RECORD variable using the UPDATE ... SET ROW statement as shown in the sample script below: CREATE TABLE emp_temp AS SELECT * FRO... 2018-08-14, 2641🔥, 0💬

SET Statements in SQL Server Transact-SQL
How to assign value to a variable in SQL Server Transact-SQL? How to use the SET statements? In Transact-SQL, you can use SET statements to assign values to variables using the assignment operator =, in the syntax of: SET @variable = &lt;value&gt; When an SET statement is executed, the syste... 2017-04-04, 2640🔥, 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, 2639🔥, 0💬

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General MySQL Oracle SQL Server