ASA SQL Reference
  SQL Statements

WHILE statement [T-SQL]

Description 

Use this statement to provide repeated execution of a statement or compound statement.

Syntax 

WHILE search-condition-statement

Usage 

The WHILE conditional affects the execution of only a single SQL statement, unless statements are grouped into a compound statement between the keywords BEGIN and END.

The BREAK statement and CONTINUE statement can be used to control execution of the statements in the compound statement. The BREAK statement terminates the loop, and execution resumes after the END keyword marking the end of the loop. The CONTINUE statement causes the WHILE loop to restart, skipping any statements after the CONTINUE.

Permissions 

None.

Side effects 

None.

See also 

LOOP statement

Standards and compatibility 

• SQL/92    Transact-SQL extension.

• SQL/99    Transact-SQL extension.

• Sybase    Supported by Adaptive Server Enterprise.

Example 

The following code illustrates the use of WHILE:

WHILE ( SELECT AVG(unit_price) FROM product ) < $30
BEGIN
   UPDATE product
   SET unit_price = unit_price + 2
   IF ( SELECT MAX(unit_price) FROM product ) > $50
      BREAK
END

The BREAK statement breaks the WHILE loop if the most expensive product has a price above $50. Otherwise, the loop continues until the average price is greater than or equal to $30.