将案例陈述值分配给变量

Question

我正在为PPK写一个函数。 如果消除了“ END AS @PPK”，则可以使此Case语句起作用，但是当我尝试将最终结果分配给变量时，出现语法错误。 谁能告诉我我错了：谢谢！

DECLARE @USL AS DECIMAL(5,2)
DECLARE @LSL AS DECIMAL(5,2)
DECLARE @AVG AS DECIMAL(5,2)
DECLARE @SDEV AS DECIMAL(5,2)

SET @USL = 6.143
SET @LSL = 2.9382
SET @AVG = 4.1
SET @SDEV = 1.6

DECLARE @PPK DECIMAL(5,2)

DECLARE @VAL1 DECIMAL(5,2)
DECLARE @VAL2 DECIMAL(5,2)

SET @VAL1 = (@USL - @AVG)/(3*@SDEV)
SET @VAL2 = (@AVG - @LSL)/(3*@SDEV)
SELECT @VAL1
SELECT @VAL2

SELECT CASE
    WHEN @VAL1 < @VAL2
    THEN @VAL1
    ELSE @VAL2 END
--END AS @PPK

Answer 1

SELECT @PPK = CASE
    WHEN @VAL1 < @VAL2
    THEN @VAL1
    ELSE @VAL2 END