General MySQL Oracle SQL Server

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Show All Indexes of a given Table in MySQL
How To Get a List of Indexes of a Given Table in MySQL? If you want to see the index you have just created for an existing table, you can use the "SHOW INDEX FROM tableName" command to get a list of all indexes in a given table. The tutorial script below shows you a nice example: mysql&gt; SHOW ... 2018-02-14, 3005🔥, 0💬

Tables Using InnoDB Storage Engine in MySQL
How To Create a New Table Using the InnoDB Storage Engine in MySQL? InnoDB storage engine was developed by Innobase Oy, which is an Oracle company now. InnoDB is transaction safe, and has been used by a number of large Websites, like Slashdot.org. InnoDB is not the default storage engine. You need t... 2017-09-01, 3004🔥, 0💬

"IS NULL" - Testing NULL Values in SQL Server
How To Test NULL Values Properly in SQL Server Transact-SQL? From previous tutorials, you learned that comparing expressions with NULL will always result NULL. So you can not use comparison operators to test if an expression represents a NULL value or not. To test expressions for NULL values, you sh... 2017-02-03, 3003🔥, 0💬

Creating Triggers for INSERT Statements Only in SQL Server
How To Create a Trigger for INSERT Only in SQL Server? The trigger, dml_message, provided in previous tutorials was defined to handle all 3 types of DML statements, INSERT, UPDATE, and DELETE. If you do not want the trigger to handle all 3 types of DML statements, you can list only 1 or 2 of the sta... 2016-10-24, 3003🔥, 0💬

Define an Anonymous Block in Oracle
How To Define an Anonymous Block in Oracle? An anonymous block must have an execution part, which is a group of other PL/SQL statements enclosed in the BEGIN ... END statement. Here is a script on how to define a simple anonymous block with SQL*Plus: SQL&gt; set serveroutput on; SQL&gt; begi... 2018-10-30, 3002🔥, 0💬

Use Subqueries in the FROM Clause in Oracle
How To Use Subqueries in the FROM Clause in Oracle? If you have a query returning many rows of data, and you want to perform another query on those rows, you can put the first query as a subquery in the FROM clause of the second query. The following statement shows you how to use a subquery as base ... 2019-09-27, 3001🔥, 0💬

Adding Address Records into AdventureWorksLT in SQL Server
How to add an address record into AdventureWorksLT in SQL Server? To find out if we can add data into AdventureWorksLT or not, you can try to add an address record into the "SalesLT.Address" in AdventureWorksLT: USE AdventureWorksLT GO INSERT SalesLT.Address (AddressLine1, City, StateProvince, Count... 2016-12-02, 3000🔥, 0💬

Use Group Functions in ORDER BY Clause in Oracle
Can Group Functions Be Used in the ORDER BY Clause in Oracle? If the query output is aggregated as groups, you can sort the groups by using group functions in the ORDER BY clause. The following statement returns how many employees are having the same salary in each department. The group output is so... 2019-10-27, 2999🔥, 0💬

Create a Single Index for Multiple Columns in Oracle
How To Create a Single Index for Multiple Columns in Oracle? If you know a group of multiple columns will be always used together as search criteria, you should create a single index for that group of columns with the "ON table_name(col1, col2, ...)" clause. Here is an example of one index for two c... 2019-04-17, 2999🔥, 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, 2999🔥, 0💬

Update Column Values on Multiple Rows in MySQL
How To Update Column Values on Multiple Rows in MySQL? If the WHERE clause in an UPDATE matches multiple rows, the SET clause will be applied to all matched rows. This rule allows you to update values on multiple rows in a single UPDATE statement. Here is a good example: mysql&gt; UPDATE fyi_lin... 2018-01-13, 2998🔥, 0💬

ALTER VIEW - Modifying Existing Views in SQL Server
How To Modify the Underlying Query of an Existing View in SQL Server? If you have an existing view, and want to change the underlying SELECT statement, you can use the "ALTER VIEW ..." statement to redefine the view. The tutorial exercise below shows you how modify an existing view: USE FyiCenterDat... 2016-11-04, 2998🔥, 0💬

Use an Explicit Cursor without OPEN Statements in Oracle
How To Use an Explicit Cursor without OPEN Statements in Oracle? If you want to open a cursor and loop through its data rows in quick way, you can use the FOR ... IN ... LOOP statement in the same way as the implicit cursor. The following tutorial exercise gives you a good example: CREATE OR REPLACE... 2018-04-07, 2997🔥, 0💬

Turn on Error Logs in MySQL
How To Turn on Error Logs in MySQL? If you want MySQL to write critical errors into a log file, you can use the "--log-error=fileName" option at the "mysqld" command line. The tutorial exercise below shows you a good example on how to use this option: &gt;cd \mysql\bin &gt;mkdir \mysql\logs ... 2017-11-29, 2996🔥, 0💬

Use DML Statements in PL/SQL in Oracle
Can DML Statements Be Used in PL/SQL in Oracle? Yes, you can run almost any DML statements in PL/SQL directly. To manipulate Oracle database data you can include INSERT, UPDATE, and DELETE statements, directly in PL/SQL programs, without any special notation, as shown in the following sample code: (... 2018-10-13, 2995🔥, 0💬

Predefined User Accounts in MySQL
What Are the Predefined User Accounts in MySQL? There is only one predefined user account called "root": "root" was created during the installation process. "root" has no password initially. You need to assign a new password as soon as you finishes the installation. "root" has all access privileges ... 2017-09-08, 2995🔥, 0💬

Enabling TCP/IP Protocol on a SQL Server
How To Enable TCP/IP Protocol on a SQL Server? By default, the TCP/IP protocol is turned off when a SQL Server is installed to reduce security risk. But if you want applications to connect and access the SQL Server, you need to enable the TCP/IP protocol on the server by following this tutorial: 1. ... 2024-07-25, 2994🔥, 0💬

Primary Key - Default Indexes of Tables in SQL Server
Is the PRIMARY KEY Column of a Table an Index in SQL Server? If you define a primary key on a table, an index for the primary key column will be created by default. The tutorial exercise below shows you the index created as part of the primary key column of "fyi_links": USE FyiCenterData; GO -- Drop... 2016-11-13, 2994🔥, 0💬

"CREATE TRIGGER" - Creating a DDL Trigger in SQL Server
How To Create a DDL Trigger using "CREATE TRIGGER" Statements in SQL Server? A DDL trigger is defined to handle a DDL statement event, like create, alter and drop tables, views, indexes, etc. DDL triggers can be used to generate warning messages on database object changes. The format of creating a D... 2016-10-22, 2994🔥, 0💬

Creating an Index for Multiple Columns in SQL Server
How To Create an Index for Multiple Columns in SQL Server? An index for multiple columns works similarly to a sorting process on multiple columns. If an index is defined for two columns, the index key is composed by values from those two columns. A multi-column index will be used to speed up the sea... 2016-11-13, 2993🔥, 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, 2993🔥, 0💬

Defining the Name and Server for a new DSN
How To Define the Name and Server for a new DSN? Continuing from the previous tutorial, on the first screen of the "Create a New Data Source to SQL Server" wizard, you should enter 3 fields: Name, Description, and Server as suggested below: Name: FYI_SQL_SERVER Description: FYIcenter.com SQL Server ... 2024-08-06, 2990🔥, 0💬

Using CASE Expression in MySQL
How To Use CASE Expression in MySQL? There are 2 ways to use the CASE expression. The first way is to return one of the predefined values based on the comparison of a given value to a list of target values. The second way is to return one of the predefined values based on a list of conditions. Here ... 2018-03-24, 2990🔥, 0💬

Inserting a New Row into a Table in MySQL
How To Insert a New Row into a Table in MySQL? To insert a new row into a table, you should use the INSERT INTO statement with values specified for all columns as shown in the following example: mysql&gt; INSERT INTO fyi_links VALUES (101, 'dev.fyicenter.com', NULL, 0, '2006-04-30'); Query OK, 1... 2018-01-16, 2989🔥, 0💬

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General MySQL Oracle SQL Server