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mysql一对多的lEFt join 怎样只关联1条

select top 1 * from book 不对,因为mysql里没有top这种写法,它用limit 查第一条 select * from book limit 1; select * from book limit 0,30 后面的limit 0,30 是查询前30条记录

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...

-- 使用 case when 就可以判断一下create table a(id int ,type int , name varchar(30) )insert into a values (1,1,'aaa')insert into a values (2,2,'bbb')insert into a values (3,1,'ccc')insert into a values (4,2,'ddd') create table b...

select * from (select T.*,ROW_NUMBER() OVER (ORDER BY b中重复字段 ) rn from (A LEFT JOIN b) T) where rn = 1 大概思路 自己研究哈 呵呵

收藏(1) sql语句如下: SELECT udd.id,udd.doTime,udd.doType,udd.isOk,udd.resourceId, udd.userId,uu.alias userName,uu.email AS email,bd.nid AS drugId,bd.drug_name_en AS drugName FROM udl_drugs_downlaod_log udd LEFT JOIN use_user u...

可以多个一起使用,例如: select * from a left join b on a.id=b.idleft join c on a.id=c.id;

select a.*,jjr_project_id,project_typeid,project_type,project_title,project_manageid,project_endtime from zhaop_jobfair_person_zhiwei a left join jjr_project b on a.jobfair_id=b.project_typeid ----这里可以直接查询对应表的单个字...

select p.name,f.id from fans f left join accounts a on f.fan_account_id=a.id left join deals d on a.id=d.account_idleft join deal_details dd on d.id=dd.deal_id left join products p on dd.relation_object=p.idorder by d.time desc...

多表连接查询 假设三个表的分别为a, b, c 以a为主表,b和c为辅表 Sql代码: select a.a as a, b.b as b, c.c as c from a left join b on a.id=b.id left join c on b.id=c.id where… 批注1:左连接按先后顺序,先是表a和表b连接,再与表c连接。...

(#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...

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