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Using WHILE...BREAK or CONTINUE

The WHILE statement repeats a statement or block of statements as long as a specified condition remains true.

Two Transact-SQL statements are commonly used with WHILE: BREAK or CONTINUE. The BREAK statement exits the innermost WHILE loop and the CONTINUE statement restarts a WHILE loop. A program might execute a BREAK statement if, for example, there are no other rows to process. A CONTINUE statement could be executed if, for example, the execution of the code should continue.

NoteNote

If a SELECT statement is used as the condition for the WHILE statement, the SELECT statement must be in parentheses.

A. Using WHILE in a cursor

The following example uses a WHILE statement to control how many fetches are done.

USE AdventureWorks;
GO
DECLARE abc CURSOR FOR
SELECT * FROM Purchasing.ShipMethod;
OPEN abc;
FETCH NEXT FROM abc
WHILE (@@FETCH_STATUS = 0)
   FETCH NEXT FROM abc;
CLOSE abc;
DEALLOCATE abc;
GO

Other valid WHILE condition tests could be the following:

WHILE (@ACounterVariable < 100)

Or

WHILE EXISTS(SELECT LastName FROM Person.Contact WHERE FirstName = N'Anne')

B. Using BREAK and CONTINUE with nested IF...ELSE and WHILE

In the following example, if the average list price of a product is less than $300, the WHILE loop doubles the prices and then selects the maximum price. If the maximum price is less than or equal to $500, the WHILE loop restarts and doubles the prices again. This loop continues doubling the prices until the maximum price is greater than $500, and then exits the WHILE loop and prints a message.

USE AdventureWorks;
GO
WHILE (SELECT AVG(ListPrice) FROM Production.Product) < $300
BEGIN
   UPDATE Production.Product
      SET ListPrice = ListPrice * 2
   SELECT MAX(ListPrice) FROM Production.Product
   IF (SELECT MAX(ListPrice) FROM Production.Product) > $500
      BREAK
   ELSE
      CONTINUE
END
PRINT 'Too much for the market to bear';


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