mysql 多张无关联表查询数据并分页
功能需求
在三张没有主外键关联的表中取出自己想要的数据，并且分页。
数据库表结构
水果表：
坚果表：
饮料表：
数据库随便建的，重在方法。
主要使用union all 操作符
union all 操作符用于合并两个或多个 select 语句的结果集。
请注意，union all内部的 select 语句必须拥有相同数量的列。列也必须拥有相似的数据类型。同时，每条 select 语句中的列的顺序必须相同 ; 另外，union all结果集中的列名总是等于 union all中第一个 select 语句中的列名。
|
1
2
3
4
5
6
7
8
9
10
|
// 详细sql语句select * from( (select fid,fname,price,type from fruits) union all (select nid,name,price,6 as type from nut) union all (select did,dname,price,7 as type from drinks) ) as fnd limit 0,10 -----fnd为表的别名 |
最终结果
mysql多表联合查询时出现的分页问题的解决
mysql一对多分页问题
部门表：tbl_dept
员工表：tbl_emp
数据库sql文件
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
|
create database /*!32312 if not exists*/`ssm-crud` /*!40100 default character set utf8 */; use `ssm-crud`; /*table structure for table `tbl_dept` */ drop table if exists `tbl_dept`; create table `tbl_dept` ( `dept_id` int(11) not null auto_increment, `dept_name` varchar(255) default null, primary key (`dept_id`)) engine=innodb auto_increment=8 default charset=utf8; /*data for the table `tbl_dept` */ insert into `tbl_dept`(`dept_id`,`dept_name`) values(1,'技术部'),(2,'业务部'),(6,'销售部'),(7,'人事部'); /*table structure for table `tbl_emp` */ drop table if exists `tbl_emp`; create table `tbl_emp` ( `emp_id` int(11) not null auto_increment, `emp_name` varchar(255) default null, `emp_gender` char(1) default null, `emp_email` varchar(255) default null, `d_id` int(11) default null, primary key (`emp_id`), key `fk_tbl_emp` (`d_id`), constraint `fk_tbl_emp` foreign key (`d_id`) references `tbl_dept` (`dept_id`)) engine=innodb auto_increment=14 default charset=utf8; /*data for the table `tbl_emp` */ insert into `tbl_emp`(`emp_id`,`emp_name`,`emp_gender`,`emp_email`,`d_id`) values(1,'xiaoshen','2',null,6),(4,'晓明','1',null,1),(5,'xiaohong','2',null,2),(6,'xiaohei','2',null,6),(7,'xiaozhang','1',null,1),(8,'xiaogao','1',null,1),(9,'xiaohua','1',null,1),(10,'xiaoyan','2',null,1),(11,'xiaohai','2',null,2),(12,'xiaoqiang','1',null,6),(13,'xiaoqi','2',null,7); |
分页错误写法(主查询员工表)
|
1
2
3
4
5
6
7
|
select * from tbl_emp eleft jointbl_dept d on d.dept_id = e.d_id limit 1,10 |
使用子查询方式解决问题
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
|
select * from ( select * from tbl_emp e left join tbl_dept d on d.dept_id = e.d_id group by e.d_id limit 1,10 ) e left join tbl_dept d on d.dept_id = e.d_id |
下面代码与之无关 仅为备份
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
|
select ft.id, ft.partner_id as partnerid, ft.code , ft.end_update_date as endupdatedate, ft.name , ft.type , ft.area , ft.is_default as isdefault, fp.id fpid, fp.shop_id as fpshopid , fp.provice_id as fpproviceid , fp.provice_name as fpprovicename , fp.start_num as fpstartnum , fp.start_fee as fpstartfee , fp.increase_num as fpincreasenum , fp.increase_fee as fpincreasefee , fp.code as fpcode , fp.provice_text as fpprovicetext , fp.template_id as fptemplateid from ( select f.id, f.partner_id , f.code , f.end_update_date , f.name , f.type , f.area , f.is_default , f.is_del, f.create_date from bus_freight_template f left join bus_freight_provice p on f.id = p.template_id where f.code = p.code and f.code = #[code] group by f.id limit #{startpage},#{pagesize} ) ft left join bus_freight_provice fp on ft.id = fp.template_id where ft.code = fp.code and fp.template_id is not null and ft.code = #[code] and fp.is_del = '0' and ft.is_del = '0' order by ft.create_date desc |
以上为个人经验，希望能给大家一个参考，也希望大家多多支持服务器之家。
原文链接：https://blog.csdn.net/qq_38159467/article/details/85015559
