本教程操作环境:Windows10系统、MySQL5.7版本、Dell G3电脑。
mysql sum求和使用方法是什么?
MySQL SUM() 带条件的求和方法与多条件的求和方法
一、单一的求和。
select sum(value) as value from table where user_id = 1 and type = 6 and type_son = 2
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value 为求和的字段。
as 后面是 sum 求和后给它一个名称。
二、SQL语句中嵌套语句多条件求和。
select (select sum(value) from table where type = 6 and type_son = 1) as xj0, (select sum(value) from table where type = 6 and type_son = 2) as xj1, (select sum(value) from table where type = 3 and type_son = 3) as xj2, (select sum(value) from table where type = 4 and type_son = 3) as xj3 from table where user_id = 1 limit 0,1
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as 后面是 sum 求和后给它一个名称,这样就不会冲突。
三、与第二个一样,但是不采取语句嵌套的方式求和,而是使用 sum 判断求和。
select sum(IF(type = 6 and type_son = 1,value,NULL)) as xj0, sum(IF(type = 6 and type_son = 2,value,NULL)) as xj1, sum(IF(type = 3 and type_son = 0,value,NULL)) as xj2, sum(IF(type = 4 and type_son = 3,value,NULL)) as xj3 from table where user_id = 1 sum(IF('条件判断','求和的字段','NULL不计算')) as '别名'
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我觉得第三个的方式比前面两个的方式要好。
YII 2.0 使用 SUM 求和
$v['alls_bonus'] = AccountingLog::find() ->select([" sum( IF(type = 6 and type_son = 1,value,NULL) ) as xj0, sum( IF(type = 6 and type_son = 4,value,NULL) ) as xj1, sum( IF(type = 8 and type_son = 4,value,NULL) ) as xj2, sum( IF(type = 3 and type_son = 1,value,NULL) ) as xj3 "]) ->where(['user_id'=>1]) ->asArray() ->one();
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注意要在 select 里面加 ["sum........"],否则会报错
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