General MySQL Oracle SQL Server

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Create an Index for a Given Table in MySQL
How To Create an Index for a Given Table in MySQL? If you have a table with a lots of rows, and you know that one of the columns will be used often as a search criteria, you can add an index for that column to improve the search performance. To add an index, you can use the "CREATE INDEX" statement ... 2018-02-14, 2448🔥, 0💬

Character String Data Types in MySQL
What Are Character String Data Types in MySQL? MySQL supports the following string data types: CHAR(n) same as CHARACTER(n) - Fixed width and " " padded characters strings. Default character set is ASCII. NCHAR(n) same as NATIONAL CHARACTER(n) - Fixed width and " " padded character strings with UTF8... 2018-04-12, 2447🔥, 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, 2445🔥, 0💬

Invoke Built-in Functions in PL/SQL in Oracle
How To Invoke Built-in Functions in PL/SQL in Oracle? Of course, you can invoke SQL functions in SQL statements. But many SQL functions can also be executed in regular PL/SQL statements, as shown in the following sample script: DECLARE now DATE; id NUMBER; str VARCHAR2(40); BEGIN now := SYSDATE; DBM... 2018-09-13, 2444🔥, 0💬

Define a Data Field as NOT NULL in Oracle
How To Define a Data Field as NOT NULL in Oracle? When defining a specific RECORD type, you can define a data field as NOT NULL to make sure variables with this RECORD type to always have values in this field. A field defined as NOT NULL must have a default value. Here is a tutorial script showing y... 2018-09-01, 2443🔥, 0💬

What Is a Table in SQL Server
What is a table in SQL Server? A table in database is a data object used to store data. Tables have the following features: Data is stored in a table with a structure of rows and columns. Columns must be pre-defined with names, types and constrains. A table object may have other associated data obje... 2016-11-20, 2443🔥, 0💬

Creating a New Table in MySQL
How To Create a New Table in MySQL? If you want to create a table, you can run the CREATE TABLE statement as shown in the following sample script: &lt;?php include "mysql_connection.php"; $sql = "CREATE TABLE fyi_links (" . " id INTEGER NOT NULL" . ", url VARCHAR(80) NOT NULL" . ", notes VARCHAR... 2017-10-08, 2442🔥, 0💬

Deleting All Rows with TRUNCATE TABLE Statement in SQL Server
How To Delete All Rows with TRUNCATE TABLE Statement in SQL Server? 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... 2016-10-30, 2441🔥, 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, 2440🔥, 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, 2440🔥, 0💬

Add Another Datafile to a Tablespace in Oracle
How To Add Another Datafile to a Tablespace in Oracle? If you created a tablespace with a data file a month ago, now 80% of the data file is used, you should add another data file to the tablespace. This can be done by using the ALTER TABLESPACE ... ADD DATAFILE statement. See the following sample s... 2019-04-09, 2439🔥, 0💬

What Is Index in MySQL
What Is Index in MySQL? An index is a single column or multiple columns defined to have values pre-sorted to speed up data retrieval speed.   ⇒ What Is View in MySQL ⇐ What Is Foreign Key in MySQL ⇑ Database Basics and Terminologies in MySQL ⇑⇑ MySQL Database Tutorials 2017-07-07, 2439🔥, 0💬

What Are Group Functions in Oracle
What Are Group Functions in Oracle? Group functions are functions applied to a group of rows. Examples of group functions are: COUNT(*) - Returns the number of rows in the group. MIN(exp) - Returns the minimum value of the expression evaluated on each row of the group. MAX(exp) - Returns the maximum... 2019-12-19, 2438🔥, 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, 2437🔥, 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, 2436🔥, 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, 2434🔥, 0💬

Retrieving the Last Sequence ID in MySQL
How To Get the Last ID Assigned by MySQL in MySQL? If you use an ID column with AUTO_INCREMENT attribute, you can use the mysql_insert_id() function to get the last ID value assigned by the MySQL server, as shown in the sample script below: &lt;?php include "mysql_connection.php"; $sql = "INSERT... 2017-09-12, 2434🔥, 0💬

UNIQUE Constraint Creating Default Index in SQL Server
Does the UNIQUE Constraint Create an Index in SQL Server? If you add the UNIQUE constraint on a column, SQL Server will automatically add a non-clustered index for that column. The tutorial exercise below shows you the index created as part of the UNIQUE column, "id", of "fyi_links": USE FyiCenterDa... 2016-11-13, 2434🔥, 0💬

Syntaxes of Creating Table-Valued Functions in SQL Server
How Many Ways to Create Table-Valued Functions in SQL Server Transact-SQL? SQL Server supports two syntaxes of creating table-valued functions: 1. Inline Table-valued Functions - A table-valued function created with a single SELECT statement: CREATE FUNCTION function_name( @parameter_1 data_type, @p... 2016-12-18, 2433🔥, 0💬

Creating a View with Data from Another View in SQL Server
Can You Create a View using Data from Another View in SQL Server? Can You Create a View with Data from Another View? The answer is yes. A view can be used as a table to build other views. The tutorial exercise below shows you how to create a view using data from another view: USE AdventureWorksLT; G... 2016-11-05, 2433🔥, 0💬

What Are DML Statements in MySQL
What Are DML Statements in MySQL? 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. UPDATE - Updating existing rows in database tables . DELETE - Deleting existing r... 2018-01-24, 2431🔥, 0💬

Define the ID Column as Auto-Incremented in MySQL
How To Define the ID Column as Auto-Incremented in MySQL? Many tables require an ID column to assign a unique ID number for each row in the table. For example, if you have a table to hold forum member profiles, you need an ID number to identify each member. To allow MySQL server to automatically ass... 2017-09-12, 2431🔥, 0💬

Entering Character Strings in MySQL
How To Include Character Strings in SQL statements in MySQL? If you want to include character strings in your SQL statements, you need to quote them in one of the following formats: Using single quotes. For example 'FYIcenter.com'. Using double quotes. For example "FYI Center". Using single quotes p... 2018-04-12, 2430🔥, 0💬

Count Number of Rows with SELECT Statements in MySQL
How To Use SELECT Statement to Count Number of Rows in MySQL? If you want to count the number of rows, you can use the COUNT(*) function in the SELECT clause. The following tutorial exercise shows you some good example: mysql&gt; SELECT COUNT(*) FROM fyi_links; +----------+ | COUNT(*) | +-------... 2018-01-06, 2430🔥, 0💬

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General MySQL Oracle SQL Server