oracle中case when与decode语句的等价转换示例

sql

WITH x AS (
SELECT 1 AS id,'a1' AS name FROM DUAL UNION ALL 
SELECT 2 AS id,null AS name FROM DUAL 
)
SELECT id
	, CASE WHEN name IS NULL THEN '我是null' ELSE '有值：' || name END AS "通过case when判断"
	, decode(name,NULL,'我是null','有值：' || name) AS "通过decode判断"
FROM X

结果