General MySQL Oracle SQL Server

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Use Existing Column Values in the SET Clause in MySQL
How To Use Existing Column Values in the SET Clause in MySQL? 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 column names in the expressions. The tutorial exer... 2018-01-13, 2549🔥, 0💬

Quoting Date and Time Values in MySQL
How To Quote Date and Time Values in SQL Statements in MySQL? If you want to provide date and time values in a SQL statement, you should write them in the format of "yyyy-mm-dd hh:mm:ss", and quoted with single quotes ('). The tutorial exercise below shows you two INSERT statements. The first one us... 2017-06-23, 2549🔥, 0💬

Quoting Text Values in MySQL
How To Quote Text Values in SQL Statements in MySQL? Text values in SQL statements should be quoted with single quotes ('). If the text value contains a single quote ('), it should be protected by replacing it with two single quotes (''). In SQL language syntax, two single quotes represents one sing... 2017-06-28, 2548🔥, 0💬

Inserting Multiple Rows with One INSERT Statement in SQL Server
How To Insert Multiple Rows with One INSERT Statement in SQL Server? If you want to insert multiple rows with a single INSERT statement, you can use a subquery instead of the VALUES clause. Rows returned from the subquery will be inserted the target table. The following tutorial exercise gives you a... 2016-11-02, 2548🔥, 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, 2547🔥, 0💬

"INSERT INTO" - Inserting a New Row into a Table in SQL Server
How To Insert a New Row into a Table with "INSERT INTO" Statements in SQL Server? To insert a new row into a table, you can use the INSERT INTO statement with values specified for all columns as in the following syntax: INSERT INTO table_name VALUES (list_of_values_of_all columns) Note that the list... 2016-11-03, 2546🔥, 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, 2545🔥, 0💬

Deleting an Existing Database in MySQL
How To Drop an Existing Database in MySQL? If want to drop an existing database from the MySQL server, you can use the DROP DATABASE statement. Here is a good example of dropping an existing database: $con = mysql_connect('localhost:8888' ,'dev', 'iyf'); $sql = 'DROP DATABASE fyi'; if (mysql_query($... 2017-10-23, 2545🔥, 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, 2544🔥, 0💬

Restrictions on External Table Columns in Oracle
What Are the Restrictions on External Table Columns in Oracle? When creating external table columns, you need to watch out some restrictions: "PRIMARY KEY" is not allowed. "NOT NULL" is not allowed. "DEFAULT value" is not allowed.   ⇒ What Is a Directory Object in Oracle ⇐ Load Data through Externa... 2016-11-27, 2544🔥, 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, 2543🔥, 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, 2543🔥, 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, 2542🔥, 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, 2541🔥, 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, 2541🔥, 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, 2540🔥, 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, 2539🔥, 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, 2539🔥, 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, 2539🔥, 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, 2538🔥, 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, 2538🔥, 0💬

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, 2537🔥, 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, 2537🔥, 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, 2537🔥, 0💬

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General MySQL Oracle SQL Server