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mysql lEFt join 重复

(#计算成人人数 SELECT tb_sell_tbfinance.order_no AS order_no0, tb_sell_tbfinance.passenger_type AS passenger_type0, COUNT(*) AS passenger_count FROM tb_sell_tbfinance GROUP BY tb_sell_tbfinance.passenger_type, tb_sell_tbfinance...

select distinct id,name,mobile,city from table1 left join table2 on table1.id = table2.table1_id;

select Sno,Sname,concat(Cname) as Cname from (select sc.Id ,s.Sname, c.Cname from SelectCourse scleft join Student s on s.Sno = sc.Sno left join Course c on c.Cid = sc.Cid) t group by Sno;

多表联合查询语句:SELECT * FROM table LEFT JOIN ...ON.... WHERE ...ORDER BY ....LIMIT .... 拿laizijiding的例子说明问题:三个表 板块表(block)、帖子表(post)、会员表(user) 如果查询 帖子列表中 帖子 是属于哪个板块和添加帖子的...

select a.*,bb.领料数量,dd.完工数量 from a left join (select 生产批号,sum(领料数量) as 领料数量 from b group by 生产批号) bb on a.生产批号=b.生产批号 left join (select cc.生产批号,sum(d.完工数量) as 完工数量 from (select distinc...

你的d表,a表和b表的关联字段在做join之前要保证唯一性.. 比如 left join (select distinct bizArea,cntNo from crm_contractbaseinfo) a on c.crtNO=a.cntNo

select id,a.name,pass,userid,age,num from a left join b on a.name=b.name and a.id=''

select * from a left join (select id,count(*) as c from b group by id) as b on a.id=b.id order by b.c desc

左连接是从左表那里返回所有的行,即使在右表中没有匹配的行,如果有多个匹配就会返回多个,所以数据没有变多。

SELECT * FROM A as a LEFT JOIN B as b ON a.type_id = b.id AND a.type_id = 1 LEFT JOIN C as c ON a.type_id = c.id AND a.type_id = 2; 基本思路就是使用JOIN ON AND命令。

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