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mysql数据库多表查询实例,mysql语句多表查询

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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)

“mysql ”多表联合查询语句怎么写?

一使用SELECT子句进行多表查询SELECT 字段名 FROM 表1,表2 … WHERE 表1字段 = 表2字段 AND 其它查询条件SELECT a.id,a.name,a.address,a.date,b.math,b.english,b.chinese FROM tb_demo065_tel AS b,tb_demo065 AS a WHERE a.id=b.id

注:在上面的的代码中,以两张表的id字段信息相同作为条件建立两表关联,但在实际开发中不应该这样使用,最好用主外键约束来实现。

1、联合查询可合并多个相似的选择查询的结果集。等同于将一个表追加到另一个表,从而实现将两个表的查询组合到一起,使用谓词为UNION或UNION ALL。联合查询时,查询结果的列标题为第一个查询语句的列标题。因此,要定义列标题必须在第一个查询语句中定义。要对联合查询结果排序时,也必须使用第一查询语句中的列名、列标题或者列序号。

2、在使用UNION 运算符时,应保证每个联合查询语句的选择列表中有相同数量的表达式,并且每个查询选择表达式应具有相同的数据类型,或是可以自动将它们转换为相同的数据类型。在自动转换时,对于数值类型,系统将低精度的数据类型转换为高精度的数据类型。

3、在包括多个查询的UNION语句中,其执行顺序是自左至右,使用括号可以改变这一执行顺序。例如:查询1 UNION (查询2 UNION 查询3)。

mysql数据库,多个表的查询操作

要点:left

join,right

join,inner

join

首先有如下两个表:

student:

id(int)

name(nvarchar)

1

a

2

b

3

c

4

d

5

e

6

f

quiz:

id(int)

score(int)

1

60

2

70

4

80

6

90

8

100

9

30

内连接:(inner

join)包括连接表的匹配行

select

student.name,quiz.score

from

quiz

inner

join

student

on

student.id=quiz.id

name

score

a

60

b

70

d

80

f

90

左连接:(left

join)包括连接表匹配行以及左连接表的所有行

select

student.name,quiz.score

from

student

left

join

quiz

on

student.id=quiz.id

name

score

a

60

b

70

c

null

d

80

e

null

f

90

右连接:(right

join)结果包括连接表的匹配行以及右连接表的所有行

select

student.name,quiz.score

from

student

right

join

quiz

on

student.id=quiz.id

name

score

a

60

b

70

d

80

f

90

null

100

null

30

当然,也可以看出左连接也可以写成右连接的形式:

select

student.name,quiz.score

from

student

right

join

quiz

on

student.id=quiz.id等价于

select

student.name,quiz.score

from

quiz

left

join

student

on

student.id=quiz.id

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