left join 和 group by 一起使用-白红宇的个人博客

发布日期：2022-09-10 02:29:33 浏览次数：1 分类：博客文章

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--1 s 连接 s2 ，如果s表要写group by 就得用括号，因为s left join s2 是一张表只能有一个group by ，所以括号抱起来

SELECT s.coun1,s2.coun2

FROM

(SELECT ssex,count() coun1 FROM student group by ssex)s
LEFT JOIN
(select ssex,count() coun2 from student where sname='赵雷' group by ssex) s2

on s.ssex=s2.ssex

--2 大的表a里面包了：s left join s2 ,s后面不能写group by ，这样s 就是一个完整的sql，无法进行left join了

SELECT coun1,coun2 FROM

(

select s.ssex,count() coun1,s2.coun2 FROM student s
LEFT JOIN (select ssex,count() coun2 from student where sname='赵雷' group by ssex) s2

on s.ssex=s2.ssex

where 1=1

group by s.ssex,s2.coun2

) a

-- sql参考

SELECT

t.cllx,

nvl( t.sumCount, 0 ) sumCount,

nvl( t1.twentyFourCount, 0 ) twentyFourCount,

nvl( t2.fortyEightCount, 0 ) fortyEightCount,

nvl( t3.seventyTwoCount, 0 ) seventyTwoCount,

nvl( t4.sevenDay, 0 ) sevenDay,

nvl( t5.yangCount, 0 ) yangCount

FROM

( SELECT cllx, count( * ) sumCount FROM T_SUP_TC_NETCAR_HS t GROUP BY cllx ) t

LEFT JOIN (

SELECT

cllx,

count( * ) twentyFourCount

FROM

T_SUP_TC_NETCAR_HS t

WHERE

to_date( t.HSRQ, 'yyyy-MM-dd hh24:mi:ss' ) > ( SYSTIMESTAMP - 1 )

GROUP BY

cllx

) t1 ON t.cllx = t1.CLLX

LEFT JOIN (

SELECT

cllx,

count( * ) fortyEightCount

FROM

T_SUP_TC_NETCAR_HS t

WHERE

to_date( t.HSRQ, 'yyyy-MM-dd hh24:mi:ss' ) > ( SYSTIMESTAMP - 2 )

GROUP BY

cllx

) t2 ON t.cllx = t2.CLLX

LEFT JOIN (

SELECT

cllx,

count( * ) seventyTwoCount

FROM

T_SUP_TC_NETCAR_HS t

WHERE

to_date( t.HSRQ, 'yyyy-MM-dd hh24:mi:ss' ) > ( SYSTIMESTAMP - 3 )

GROUP BY

cllx

) t3 ON t.cllx = t3.CLLX

LEFT JOIN (

SELECT

cllx,

count( * ) sevenDay

FROM

T_SUP_TC_NETCAR_HS t

WHERE

to_date( t.HSRQ, 'yyyy-MM-dd hh24:mi:ss' ) > ( SYSTIMESTAMP - 7 )

GROUP BY

cllx

) t4 ON t.cllx = t4.CLLX

LEFT JOIN ( SELECT cllx, count( * ) yangCount FROM T_SUP_TC_NETCAR_HS t WHERE t.hsjg like '%阳%' GROUP BY cllx ) t5 ON t.cllx = t5.CLLX

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