Difference between revisions of "SQL statement examples"

Revision as of 09:35, 23 July 2015

This article demonstrates a variety of SQL statements.

Overview

SQL statements, broadly speaking, fall into four commonly used categories:

• SELECT statements return zero or more records
• INSERT INTO statements insert a new record
• UPDATE statements update existing records
• DELETE statements delete existing records

Case insensitivity

SQL statements are typically case-insensitive. These examples follow the common convention of uppercasing SQL keywords.

SELECT statements

SELECT statement return zero or more records.

Syntax:

SELECT column_name,column_name FROM table_name;

Example:

...

INSERT INTO statements

INSERT INTO statements insert a new record into a database table.

The INSERT INTO statement has two forms:

• Specify values, do not specify columns
• Specify values and columns

Syntax (first form):

INSERT INTO table_name VALUES (value1,value2,value3,...);/code>

Syntax (second form):

<code>INSERT INTO table_name (column1,column2,column3,...) VALUES (value1,value2,value3,...);

Example:

...

UPDATE statements

UPDATE statements update zero or more existing records in a database table.

Syntax:

UPDATE table_name SET column1=value1,column2=value2,... WHERE some_column=some_value;

Example:

...

DELETE statements

DELETE statements delete zero or more existing records from a database table.

Syntax:

DELETE FROM table_name WHERE some_column=some_value;

If the WHERE clause is omitted, the DELETE query will delete all records in the specified table.

Example:

DELETE FROM j_error_prod WHERE Fk_Error = 99 AND Fk_Prod = 999

Different implementations of SQL

Note that different implementations of SQL -- different "flavors" -- may differ in their details. The examples on this page are appropriate to a wide range -- but not necessarily all -- implementations.

External links

• SQL SELECT @ W3Schools
• SQL INSERT INTO @ W3Schools
• SQL UPDATE @ W3Schools
• SQL DELETE @ W3Schools