SQL if else 判断的写法

1、语法：  字段1 IS NULL THEN '空' ELSE '不为空' END AS STATUS

SELECT

plan.aaaa,

plan.bbbb,

ecn.PUID,

TO_CHAR( app.PCREATION_DATE, 'YYYY' ) AS year,

TO_CHAR( app.PCREATION_DATE, 'mm' ) AS month,

CASE WHEN worksp.PDATE_RELEASED IS NULL THEN '未完成' ELSE '已完成' END AS STATUS

　　在Oracle 中可用，其他数据库没有测试过