mysql一条sql查出多个条件不同的sum或count问题
作者：码农王山
这篇文章主要介绍了mysql一条sql查出多个条件不同的sum或count问题，具有很好的参考价值，希望对大家有所帮助。如有错误或未考虑完全的地方，望不吝赐教
一条sql查出多个条件不同的sum或count
最近做java后台遇到很多问题记录一下，有个需求是在一条sql中同时统计到几条条件不一样的sql或count，就用了子查询，希望能帮助到需要的朋友，上代码和效果图：
select
sum(pzgwjscd) as allJsgm,sbjh.nd as nd,
( select sum(pzgwjscd) from fm_jh_ws_ptgw ptgw left join fm_sb_jh sbjh on ptgw.sbid = sbjh.id
where substring(ptgw.xzqh,1,4) LIKE CONCAT ('3301') and ptgw.zt != 0 and sbjh.nd=2017 ) as hzJsgm,
( select sum(pzgwjscd) from fm_jh_ws_ptgw ptgw left join fm_sb_jh sbjh on ptgw.sbid = sbjh.id
where substring(ptgw.xzqh,1,4) LIKE CONCAT ('3303') and ptgw.zt != 0 and sbjh.nd=2017) as wzJsgm,
( select sum(pzgwjscd) from fm_jh_ws_ptgw ptgw left join fm_sb_jh sbjh on ptgw.sbid = sbjh.id
where substring(ptgw.xzqh,1,4) LIKE CONCAT ('3304') and ptgw.zt != 0 and sbjh.nd=2017 ) as jxJsgm,
( select sum(pzgwjscd) from fm_jh_ws_ptgw ptgw left join fm_sb_jh sbjh on ptgw.sbid = sbjh.id
where substring(ptgw.xzqh,1,4) LIKE CONCAT ('3305') and ptgw.zt != 0 and sbjh.nd=2017) as huzJsgm,
( select sum(pzgwjscd) from fm_jh_ws_ptgw ptgw left join fm_sb_jh sbjh on ptgw.sbid = sbjh.id
where substring(ptgw.xzqh,1,4) LIKE CONCAT ('3306') and ptgw.zt != 0 and sbjh.nd=2017 ) as sxJsgm,
( select sum(pzgwjscd) from fm_jh_ws_ptgw ptgw left join fm_sb_jh sbjh on ptgw.sbid = sbjh.id
where substring(ptgw.xzqh,1,4) LIKE CONCAT ('3307') and ptgw.zt != 0 and sbjh.nd=2017 ) as jhJsgm,
( select sum(pzgwjscd) from fm_jh_ws_ptgw ptgw left join fm_sb_jh sbjh on ptgw.sbid = sbjh.id
where substring(ptgw.xzqh,1,4) LIKE CONCAT ('3308') and ptgw.zt != 0 and sbjh.nd=2017 ) as qzJsgm,
( select sum(pzgwjscd) from fm_jh_ws_ptgw ptgw left join fm_sb_jh sbjh on ptgw.sbid = sbjh.id
where substring(ptgw.xzqh,1,4) LIKE CONCAT ('3309') and ptgw.zt != 0 and sbjh.nd=2017 ) as zsJsgm,
( select sum(pzgwjscd) from fm_jh_ws_ptgw ptgw left join fm_sb_jh sbjh on ptgw.sbid = sbjh.id
where substring(ptgw.xzqh,1,4) LIKE CONCAT ('3310') and ptgw.zt != 0 and sbjh.nd=2017 ) as tzJsgm,
( select sum(pzgwjscd) from fm_jh_ws_ptgw ptgw left join fm_sb_jh sbjh on ptgw.sbid = sbjh.id
where substring(ptgw.xzqh,1,4) LIKE CONCAT ('3311') and ptgw.zt != 0 and sbjh.nd=2017 ) as lsJsgm
from fm_jh_ws_ptgw ptgw
left join fm_sb_jh sbjh on ptgw.sbid = sbjh.id
where 1=1 and ptgw.zt != 0 and sbjh.nd=2017 数据库表
查询结果：
Sql根据不同条件统计总数
经常会遇到根据不同的条件统计总数的问题，一般有两种写法：count和sum都可以
数据准备：
方法一 ：Count
代码：
SELECT COUNT( CASE WHEN age > 20 AND age < 25 THEN 1 ELSE NULL END ) AS cnt0, COUNT( CASE WHEN age >= 25 AND age < 30 THEN 1 ELSE NULL END ) AS cnt1 FROM USER;
结果：
方法二：sum
代码：
SELECT SUM( CASE WHEN age > 20 AND age < 25 THEN 1 ELSE 0 END ) AS cnt0, SUM( CASE WHEN age >= 25 AND age < 30 THEN 1 ELSE 0 END ) AS cnt1 FROM USER;
结果：
当然也可以和count代码一样ELSE后面也写为NULL
SELECT SUM( CASE WHEN age > 20 AND age < 25 THEN 1 ELSE NULL END ) AS cnt0, SUM( CASE WHEN age >= 25 AND age < 30 THEN 1 ELSE NULL END ) AS cnt1 FROM USER;
后记
其实原理很简单，count统计的时候有满足条件的就加1，没有满足的变为NULL，我们知道聚合函数统计的时候是忽略null值的；而sum原理和coun相似，不过ELSE后面可以是0或者NULL。
总结
以上为个人经验，希望能给大家一个参考，也希望大家多多支持脚本之家。