SQL Server Process Control

Process Control Statements:

BEGIN ... END	WAITFOR	Goto
While	IF ... ELSE	Break
RETURN	Continure

1.BEGIN ... END

BEGIN ... The end statement is used to combine multiple Transact-SQL statements into a single logical block. When a Process Control statement must execute a block of statements that contains two or more T-SQL statements, use begin ... End statement.

1   BEGIN 2   {sql_statement ...} 3   END

2.IF

1 IF < conditional expression >2  | program Block}

IF ... ELSE

1   IF < conditional expressions >2     | program Block 1} 3   ELSE 4     | Program Block 2}

Code:

1 Declare @x int2   Set @x=43   if @x%2=04   Print '@x is even'5   Else6   Print '@x is an odd number'

：

3.CASE

1  Case input_expression 2      when  Then result_expression 3     [...n] 4     5     ELSE else_result_expression 6 7     END

Code:

1    UsePractice2   Go3   Select *Note= Case4    whenSex='Girl'  Then 'female'5    whenSex=' Boy'   Then 'male'6   Else 'not recognized'7   End8    fromInfo_stu

Effect:

4.WHILE

Code:

1 DECLARE @n int,@sum int2   Set @n=13 Set @sum=04  while @n<=Ten5   begin6   Set @sum=@sum+@n7   Set @n=@n+18   End9   Print @sum

Effect:

SQL Server Process Control