MySQL 多表查询

我不是很了解你想要的是怎么样。以下是我的思路：select A.survey_id, A.topic, A.qid, B.options, B.description from survey_single_choice as A left join survey_single_choice_option as B on A.id = B.single_choice_id 查出单选

select A1.survey_id, A1.topic, A1.qid, B1.options, B1.description from survey_multiple_choices as A1 left join survey_multiple_choices_option as B1 on A1.id = B1.single_choice_id 查出多选

select S.name, S.description, S.status, C1.topic, C1.qid, C1.options, C1.description from survey as S left join (select A.survey_id, A.topic, A.qid, B.options, B.description from survey_single_choice as A left join survey_single_choice_option as B on A.id = B.single_choice_id) as C1 on S.id = C1.survey_id 单选合并到问卷

select S2.name, S2.description, S2.status, C2.topic, C2.qid, C2.options, C2.description from survey as S2 left join (select A1.survey_id, A1.topic, A1.qid, B1.options, B1.description from survey_multiple_choices as A1 left join survey_multiple_choices_option as B1 on A1.id = B1.single_choice_id) as C2 on S2.id = C2.survey_id 多选合并到问卷

select S3.name, S3.description, S3.status, B2.topic, B2.qid from survey as S3 left join survey_short_answer as B2 on S3.id = B2.survey_id 简答表合并到问卷

如果你是要多行列出 问卷名 题号 题目select S.name, S.description, S.status, C1.topic, C1.qid from survey as S left join (select A.survey_id, A.topic, A.qid, B.options, B.description from survey_single_choice as A left join survey_single_choice_option as B on A.id = B.single_choice_id) as C1 on S.id = C1.survey_idUNION ALLselect S2.name, S2.description, S2.status, C2.topic, C2.qid from survey as S2 left join (select A1.survey_id, A1.topic, A1.qid, B1.options, B1.description from survey_multiple_choices as A1 left join survey_multiple_choices_option as B1 on A1.id = B1.multiple_choices) as C2 on S2.id = C2.survey_idUNION ALLselect S3.name, S3.description, S3.status, B2.topic, B2.qid from survey as S3 left join survey_short_answer as B2 on S3.id = B2.survey_idORDER BY name, qid ASC

如果是一条列出select * from (select * from (select S.name, S.description, S.status, C1.topic, C1.qid, C1.options, C1.description from survey as S left join (select A.survey_id, A.topic, A.qid, B.options, B.description from survey_single_choice as A left join survey_single_choice_option as B on A.id = B.single_choice_id) as C1 on S.id = C1.survey_id) as D left join (select S2.name, S2.description, S2.status, C2.topic, C2.qid, C2.options, C2.description from survey as S2 left join (select A1.survey_id, A1.topic, A1.qid, B1.options, B1.description from survey_multiple_choices as A1 left join survey_multiple_choices_option as B1 on A1.id = B1.single_choice_id) as C2 on S2.id = C2.survey_id) as D1 on D.name = D1.name) as E left join (select S3.name, S3.description, S3.status, B2.topic, B2.qid from survey as S3 left join survey_short_answer as B2 on S3.id = B2.survey_id) E1 on E.name = E1.name

（注意：要修改*号列出你想列的列名，并改一下选项里面的列名）

你的图片看不怎么清楚，我给你写个栗子

select b.classname,count(a.sno) as 总人数 from student a,classes b where a.sno=b.sno group by b.classname

创建表，数据

create table a

(id int,

项目号 varchar(2),

总金额 int,

上家单位 varchar(4))

insert into a values (1,'01',100,'AAAA')

insert into a values (2,'02',200,'BBBB')

insert into a values (3,'03',250,'CCCC')

create table b

(id int,

项目号 varchar(2),

到款 int,

到款时间 date)

insert into b values (1,'03',50,'2018-07-23')

insert into b values (2,'03',100,'2018-07-24')

insert into b values (3,'01',80,'2018-07-25')

执行：

SELECT

a.项目号,

a.总金额,

sum(

CASE

WHEN a.项目号 = b.项目号 THEN

到款

ELSE

0

END

) 到款总额

FROM

a

LEFT JOIN b ON a.项目号 = b.项目号

GROUP BY

a.项目号,

a.总金额

结果：

---