General MySQL Oracle SQL Server

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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, 2622🔥, 0💬

Evaluating Expressions with SELECT Statements in MySQL
How To Calculate Expressions with SELECT Statements in MySQL? There is no special SQL statements to calculate expressions. But you can use the "SELECT expression FROM DUAL" statement return the calculated value of an expression. "DUAL" is a dummy table in the server. The tutorial exercise below show... 2018-04-12, 2621🔥, 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, 2621🔥, 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, 2620🔥, 0💬

Recover a Dropped Table in Oracle
How To Recover a Dropped Table in Oracle? If you accidentally dropped a table, can you recover it back? The answer is yes, if you have the recycle bin feature turned on. You can use the FLASHBACK TABLE ... TO BEFORE DROP statement to recover a dropped table from the recycle bin as shown in the follo... 2019-05-14, 2619🔥, 0💬

Numeric Data Types in MySQL
What Are Numeric Data Types in MySQL? MySQL supports the following numeric data types: BIT(n) - An integer with n bits. BOOL same as BOOLEAN - Boolean values stored in 1 bit. TINYINT - A small integer stored in 1 byte. SMALLINT - A small integer stored in 2 bytes. MEDIUMINT - A medium integer stored... 2018-01-19, 2619🔥, 0💬

Drop an Existing Index in Oracle
How To Drop an Existing Index in Oracle? If you don't need an existing index any more, you should delete it with the DROP INDEX statement. Here is an example SQL script: CREATE TABLE student (id NUMBER(5) PRIMARY KEY, first_name VARCHAR(80) NOT NULL, last_name VARCHAR(80) NOT NULL, birth_date DATE N... 2020-02-20, 2617🔥, 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, 2617🔥, 0💬

What Are User Privileges in MySQL
What Are User Privileges in MySQL? MySQL offers many user privileges to control user accesses to different functions and data objects. Here are some commonly used privileges: ALL - All privileges. CREATE - Allows the user to use CREATE TABLE commands. ALTER - Allows the user to use ALTER TABLE comma... 2017-12-09, 2616🔥, 0💬

Using Cursors in SQL Server Transact-SQL
Where to find answers to frequently asked questions on Using Cursors in SQL Server Transact-SQL? I want to loop through rows in a result set. Here is a list of frequently asked questions and their answers compiled by FYIcenter.com DBA team on Using Cursors in SQL Server Transact-SQL. Clear explanati... 2016-10-17, 2616🔥, 0💬

Types of Tables Supported by Oracle in Oracle
How Many Types of Tables Supported by Oracle in Oracle? Oracle supports 4 types of tables based on how data is organized in storage: Ordinary (heap-organized) table - This is the basic, general purpose type of table. Its data is stored as an unordered collection (heap) Clustered table - A clustered ... 2019-06-01, 2615🔥, 0💬

Supported Transaction Isolation Levels in Oracle
What Are Transaction Isolation Levels Supported by Oracle in Oracle? Oracle supports two transaction isolation levels: READ COMMITTED (the default option). If the transaction contains DML that requires row locks held by another transaction, then the DML statement waits until the row locks are releas... 2019-08-19, 2614🔥, 0💬

Convert Character Types to Numeric Types in Oracle
How To Convert Character Types to Numeric Types in Oracle? You can convert character types to numeric types in two ways: Explicitly by using TO_NUMBER() function. Implicitly by putting character data in a numeric operation. The sample script below shows you how to convert character types to numeric ... 2018-11-17, 2614🔥, 0💬

PL/SQL Procedure in Oracle
What Is a Procedure in Oracle? A procedure is a named program unit. It consists of three parts: Declaration Part - Defining the procedure name, calling parameters, local variables and local procedures. Declaration part is required. Execution Part - Defining execution logic with executable statements... 2018-11-29, 2613🔥, 0💬

Use "mysql" to Run SQL Statements in MySQL
How To Use "mysql" to Run SQL Statements in MySQL? If you want to run SQL statement to your server with "mysql", you need to start "mysql" and enter your SQL statement at the "mysql" prompt. Here is a good tutorial exercise that shows you how to run two SQL statements with "mysql": &gt;cd \mysql... 2018-02-28, 2613🔥, 0💬

Verify Time Precision in SQL Server Transact-SQL
How to verify the precession of the server system time in SQL Server Transact-SQL? You can run a WHILE loop to check the precision of server system time in Transact-SQL as shown below: DECLARE @var DATETIME2(7); DECLARE @count INT = 0; WHILE @count&lt;100 BEGIN SET @count = @count + 1; SET @var ... 2017-02-22, 2612🔥, 0💬

SELECT Statements with JOIN and Subqueries in MySQL
Where to find answers to frequently asked questions on SELECT Statements with JOIN and Subqueries in MySQL? Here is a list of frequently asked questions and their answers compiled by FYIcenter.com DBA team on SELECT Statements with JOIN and Subqueries in MySQL. Clear answers are provided with tutori... 2017-12-31, 2611🔥, 0💬

Query with a Right Outer Join in Oracle
How To Write a Query with a Right Outer Join in Oracle? If you want to query from two tables with a right outer join, you can use the RIGHT OUTER JOIN ... ON clause in the FROM clause. The following query returns output with a right outer join from two tables: departments and employees. The join con... 2019-10-18, 2610🔥, 0💬

Differences of CHAR and NCHAR in SQL Server Transact-SQL
What Are the Differences between CHAR and NCHAR in SQL Server Transact-SQL? Both CHAR and NCHAR are fixed length data types in Transact-SQL. But they have the following main differences: CHAR stores characters based on the code page with 1 byte per character most of the time. NCHAR stores characters... 2017-04-04, 2610🔥, 0💬

Difference Between Clustered and Non-Clustered Indexes in SQL Server
What Is the Difference Between Clustered and Non-Clustered Indexes in SQL Server? SQL Server 2005 supports two types of indexes: clustered index and non-clustered index. Here are the main differences between them: One table can only have only one clustered index. One table can only have many non-clu... 2016-11-13, 2610🔥, 0💬

Turn On and Off Recycle Bin for the Instance in Oracle
How To Turn On or Off Recycle Bin for the Instance in Oracle? You can turn on or off the recycle bin feature for an instance in the instance parameter file with "recyclebin=on/off". You can also turn on or off the recycle bin feature on the running instance with a SQL*Plus command, if you log in as ... 2019-05-14, 2609🔥, 0💬

Loop through a Cursor Variable in Oracle
How To Loop through a Cursor Variable in Oracle? Once a cursor variable is opened with a query statement, it will have the same attributes as a normal cursor and it can be used in the same way a normal cursor too. The following sample script shows you how to loop through a cursor variable: CREATE OR... 2018-07-18, 2609🔥, 0💬

Who Is the Owner of a Schema in SQL Server
Who Is the Owner of a Schema in SQL Server? When you create a schema in a database, SQL Server will assign a owner (a database user) to this schema. If your login name is mapped to the owner of a schema at the database level, you have the full permission on all objects in this schema. The following ... 2016-10-22, 2608🔥, 0💬

Performing Comparison on Exact Numbers in SQL Server
How To Perform Comparison on Exact Numbers in SQL Server Transact-SQL? Comparison operations on exact numbers of data types: BIT, INT, NUMERIC, etc., are very easy to understand. Here are some simple examples: -- BIT value comparison DECLARE @x BIT, @y BIT; SET @x = 0; SET @y = 1; SELECT CASE WHEN @... 2017-01-21, 2607🔥, 0💬

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General MySQL Oracle SQL Server