MyBatis Plus 如何實現連表查詢

gitee

github

在專案中新增依賴

>

>
com.github.yulichanggroupid
>
>
mybatis-plus-joinartifactid
>
>
1.1.8version
>
dependency
>

注意: mybatis plus version >= 3.4.0

service繼承mpjbaseservice (可選)

serviceimpl繼承mpjbaseserviceimpl (可選)

mpjbaseservice 繼承了iservice,同樣新增以上方法

mpjbaseserviceimpl 繼承了serviceimpl,同樣新增了以上方法

簡單的3表查詢

class

test
}

select 

t.id,
t.name,
t.***,
t.head_img,
t1.tel,
t1.address as useraddress,
t2.province,
t2.city 
from 
user t 
left join user_address t1 on t1.user_id = t.id 
left join area t2 on t2.id = t1.area_id 
where (
t.id = ? 
and t1.tel like ? 
and t.id > ?)

分頁查詢

class

test
}

select 

t.id,
t.name,
t.***,
t.head_img,
t1.tel,
t1.address as useraddress,
t2.province,
t2.city
from 
user t
left join user_address t1 on t1.user_id = t.id
left join area t2 on t2.id = t1.area_id
limit ?,?

class

test
}

select 

t.id,
t.name,
t.***,
t.head_img,
addr.tel,
addr.address,
a.province
from 
user t
left join user_address addr on t.id = addr.user_id
right join area a on addr.area_id = a.id
where (
addr.tel like ?
and a.province <= ?)

分頁查詢

class

test
}

select 

t.id,
t.name,
t.***,
t.head_img,
addr.tel,
addr.address,
a.province
from 
user t
left join user_address addr on t.id = addr.user_id
right join area a on addr.area_id = a.id 
limit ?,?

class

test
}

select 

t.id,
t.name,
t.***,
t.head_img,
addr.tel,
addr.address,
case t.*** when '男' then '1' else '0' end as ***,
sum(a.province) as province
from 
user t
left join (select * from user_address) addr on t.id = addr.user_id
right join area a on addr.area_id = a.id
where (
addr.tel like ?
and a.province <= ?)
order by
addr.id desc

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