case when 判断_sqlservercase用法

SELECT
CASE
		id 
		WHEN 21 THEN
		'aaaaa' 
		WHEN 22 THEN
		'bbbbb' ELSE '其他' 
	END 
	FROM
		hrmresource 
	WHERE
	id = 23

SELECT
	(
	CASE
			
			WHEN a.id = 21 THEN
			( SELECT id FROM hrmresource WHERE id IN ( 21 ) ) 
			WHEN a.id = 22 THEN
			( SELECT id FROM hrmresource WHERE id IN ( 22 ) ) ELSE '0' 
		END 
	) 
	FROM
		hrmresource a 
	WHERE
		id = 21
	```