General MySQL Oracle SQL Server

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"INSTEAD OF" - Overriding DML Statements with Triggers in SQL Server
How To Override DML Statements with Triggers in SQL Server? Sometime, you may want to implement some business logics in a DML trigger to cancel the DML statement. For example, you may want to check the new email address format provided by the UPDATE statement. If the email address is invalid, you to... 2016-10-22, 2541🔥, 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, 2540🔥, 0💬

Returning the Second 5 Rows from a Query in SQL Server
How To Return the Second 5 Rows in SQL Server? If you want to display query output in multiple pages with 5 rows per page, and the visitor wants to see the output for the second page, you need to display query output from row 6 to row 10. If you are using MySQL server, you can use the "LIMIT startRo... 2016-10-29, 2540🔥, 0💬

Loop through the Implicit Cursor in Oracle
How To Loop through Data Rows in the Implicit Curosr in Oracle? You use the FOR ... IN ... LOOP statement to loop through data rows in the implicit cursor as the following syntax: FOR row IN dml_statement LOOP (statement block with row.field) END LOOP; Here "row" is a local RECORD type variable with... 2018-07-22, 2538🔥, 0💬

Drop an Existing Index in MySQL
How To Drop an Existing Index in MySQL? If you don't need an existing index any more, you should delete it with the "DROP INDEX indexName ON tableName" statement. Here is an example SQL script: mysql&gt; DROP INDEX tip_subject ON tip; Query OK, 0 rows affected (0.13 sec) Records: 0 Duplicates: 0... 2018-02-14, 2538🔥, 0💬

Query with a Full Outer Join in MySQL
How To Write a Query with a Full Outer Join in MySQL? There is no way to do full outer join in MySQL. It does not support this feature at the current MySQL release.   ⇒ Inner Join with the WHERE Clause in MySQL ⇐ Query with a Right Outer Join in MySQL ⇑ SELECT Statements with JOIN and Subqueries in... 2017-09-28, 2538🔥, 0💬

CREATE CLUSTERED INDEX - Adding Clustered Indexes in SQL Server
How To Create a Clustered Index in SQL Server? If there is no primary key in a table, you can add one clustered index to that table with CREATE CLUSTERED INDEX statement. The tutorial exercise below shows you how to create a clustered index: USE FyiCenterData; GO -- Drop the old table, if needed DRO... 2016-11-13, 2538🔥, 0💬

Define an Explicit Cursor in Oracle
How To Define an Explicit Cursor in Oracle? An explicit cursor must be defined in the declaration part of a procedure or function with the CURSOR ... IS statement as shown in the following sample script: DECLARE CURSOR c_list IS SELECT * FROM countries; CURSOR t_list IS SELECT * FROM employees WHERE... 2018-07-22, 2537🔥, 0💬

Running SQL Server 2005 Books Online on Your Local System in SQL Server
How to run SQL Server 2005 Books Online on your local system in SQL Server? SQL Server 2005 Books Online can be accessed by a Web browser over the Internet. But you can also download it and read it on your local system. If you have downloaded and installed SQL Server 2005 Books Online package, you f... 2016-12-04, 2537🔥, 0💬

Getting a List of All Databases on the Server in SQL Server
How to get a list all databases on the SQL server in SQL Server? If you don't remember database names you have created, you can get a list of all databases on the server by query the "sys.databases" view as shown in this tutorial example: CREATE DATABASE FyiCenterData GO SELECT name, database_id, cr... 2016-11-24, 2537🔥, 0💬

"CREATE TRIGGER" - Creating a DML Trigger in SQL Server
How To Create a DML Trigger using CREATE TRIGGER Statements in SQL Server? A DML trigger is a trigger declared to handle a DML event, which occurs when an INSERT, UPDATE or DELETE statement is executed. If you want to create a DML trigger, you should use the "CREATE TRIGGER" statement in the followi... 2016-10-25, 2537🔥, 0💬

What Is Commit in MySQL
What Is Commit in MySQL? Commit is a way to terminate a transaction with all database changes to be saved permanently to the database server.   ⇒ What Is RollBack in MySQL ⇐ What Is Transaction in MySQL ⇑ Database Basics and Terminologies in MySQL ⇑⇑ MySQL Database Tutorials 2016-10-16, 2537🔥, 0💬

Use Subqueries with the IN Operator in Oracle
How To Use Subqueries with the IN Operator in Oracle? 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 ... 2019-09-27, 2536🔥, 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, 2536🔥, 0💬

Execute SQL Statements in MySQL
How To Execute a SQL Statement in MySQL? You can run any types of SQL statements through the mysql_query() function. It takes the SQL statement as a string and returns different types of data depending on the SQL statement type and execution status: Returning FALSE, if the execution failed. Returnin... 2017-10-23, 2535🔥, 0💬

Use Variables in SQL Statements in Oracle
Can Variables Be Used in SQL Statements in Oracle? Yes, you can use variables in SQL statements as part of any expressions. The tutorial script provides you some good examples: (Connect to XE with SQL*Plus) CREATE TABLE student (id NUMBER(5) PRIMARY KEY, first_name VARCHAR(80) NOT NULL, last_name VA... 2018-09-24, 2533🔥, 0💬

Count Duplicated Values in a Column in Oracle
How To Count Duplicated Values in a Column in Oracle? If you have a column with duplicated values, and you want to know what are those duplicated values are and how many duplicates are there for each of those values, you can use the GROUP BY ... HAVING clause as shown in the following example. It re... 2019-11-21, 2532🔥, 0💬

Use Group Functions in the SELECT Clause in Oracle
How To Use Group Functions in the SELECT Clause in Oracle? 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 4 values ca... 2019-11-21, 2532🔥, 0💬

Concatenating Character Strings in MySQL
How To Concatenate Two Character Strings in MySQL? If you want concatenate multiple character strings into one, you need to use the CONCAT() function. Here are some good examples: SELECT CONCAT('Welcome',' to') FROM DUAL; Welcome to SELECT CONCAT('FYI','center','.com') FROM DUAL; FYIcenter.com   ⇒ E... 2018-04-07, 2532🔥, 0💬

Ways to Start MySQL Server in MySQL
How To Start MySQL Server Daemon mysqld in MySQL? There are a number of ways to start MySQL server daemon, mysqld: Double click on the file name, mysqld.exe, in a file explorer window. This is an easy way to start the server. But you will not be able to specify any command line options. Enter "mysql... 2017-12-04, 2531🔥, 0💬

CURRENT_USER() - Authentication Name of Current User
How to obtain the authentication name of the current user using the CURRENT_USER() function? CURRENT_USER() is a MySQL built-in function that returns the authentication name of the current user. The authentication name is a combination of "User" and "Host" columns in the mysql.user table and used to... 2025-06-18, 2530🔥, 0💬

Use Existing Column Values in SET Clause in Oracle
How To Use Existing Values in UPDATE Statements in Oracle? 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 columns in the expressions. The tutorial exercise bel... 2020-01-21, 2530🔥, 0💬

Close MySQL Connection Objects in MySQL
How To Close MySQL Connection Objects in MySQL? MySQL connection objects created with mysql_connect() calls should be closed as soon as you have finished all of your database access needs by calling mysql_close($con) function. This will reduce the consumption of connection resources on your MySQL se... 2017-11-11, 2530🔥, 0💬

SQL Server Connection Concepts
Where to find answers to frequently asked questions on SQL Server Connection Concepts? Here is a list of frequently asked questions and their answers compiled by FYIcenter.com DBA team on SQL Server Connectivity Concepts. SQL Server Connection Protocols SQL Server TCP/IP Connection Info   ⇒ SQL Serv... 2024-08-14, 2529🔥, 0💬

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General MySQL Oracle SQL Server