case when用法总结

第一种：

SELECT tsi.`id`,tsi.`si_name`,COUNT(*) AS total, SUM(CASE WHEN ts.`GENDER`=0 THEN 1 ELSE 0 END) AS boy, SUM(CASE WHEN ts.`GENDER`=1 THEN 1 ELSE 0 END) AS girl, SUM(CASE WHEN ts.`GENDER`=0 THEN 1 ELSE 0 END)/COUNT(1) bPro, SUM(CASE WHEN ts.`GENDER`=1 THEN 1 ELSE 0 END)/COUNT(1) gPro FROM lh_tm_student ts LEFT JOIN lh_tm_school_info tsi ON tsi.`id` = ts.`DEPT_KEY` WHERE 1 = 1 AND tsi.`id` IS NOT NULL AND tsi.`pid` = #{params.deptId} GROUP BY ts.`DEPT_KEY`