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README.md
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@ -2,12 +2,6 @@
支持连表查询的[mybatis-plus](https://gitee.com/baomidou/mybatis-plus) 支持连表查询的[mybatis-plus](https://gitee.com/baomidou/mybatis-plus)
## 运行环境
* mysql8
* jdk8
* mybatis-plus 3.4.2
## 使用方法 ## 使用方法
### 方法一 ### 方法一
@ -47,6 +41,7 @@
## MyQuery用法 ## MyQuery用法
### 简单的3表查询 ### 简单的3表查询
```java ```java
class test { class test {
@Resource @Resource
@ -54,55 +49,54 @@ class test {
void testJoin() { void testJoin() {
List<UserDTO> list = userMapper.selectJoinList(UserDTO.class, List<UserDTO> list = userMapper.selectJoinList(UserDTO.class,
new MyLambdaQuery<UserDO>() new MyLambdaQuery<UserDO>()
.selectAll(UserDO.class) .selectAll(UserDO.class)
.select("addr.tel", "addr.address") .select("addr.tel", "addr.address")
.select("a.province") .select("a.province")
.leftJoin("user_address addr on t.id = addr.user_id") .leftJoin("user_address addr on t.id = addr.user_id")
.rightJoin("area a on addr.area_id = a.id") .rightJoin("area a on addr.area_id = a.id")
.gt(true, UserDO::getId, 1) .gt(true, UserDO::getId, 1)
.eq(true, UserDO::getSex, "男") .eq(true, UserDO::getSex, "男")
.stringQuery() .stringQuery()
.like(true, "addr.tel", "1") .like(true, "addr.tel", "1")
.le(true, "a.province", "1")); .le(true, "a.province", "1"));
} }
} }
``` ```
对应sql 对应sql
```sql ```sql
SELECT SELECT t.id,
t.id, t.name,
t.name, t.sex,
t.sex, t.head_img,
t.head_img, addr.tel,
addr.tel, addr.address,
addr.address, a.province
a.province FROM user t
FROM LEFT JOIN user_address addr on t.id = addr.user_id
user t RIGHT JOIN area a on addr.area_id = a.id
LEFT JOIN user_address addr on t.id = addr.user_id
RIGHT JOIN area a on addr.area_id = a.id
WHERE ( WHERE (
t.id > ? t.id > ?
AND t.sex = ? AND t.sex = ?
AND addr.tel LIKE ? AND addr.tel LIKE ?
AND a.province <= ?) AND a.province <= ?)
``` ```
说明: 说明:
* UserDTO.class 查询结果类(resultType) * UserDTO.class 查询结果类(resultType)
* selectAll(UserDO.class) 查询主表全部字段(主表实体类) * selectAll(UserDO.class) 查询主表全部字段(主表实体类)
* select() mp的select策略是覆盖,以最后一次为准,这里的策略是追加,可以一直select * select() mp的select策略是覆盖,以最后一次为准,这里的策略是追加,可以一直select
主表字段可以用lambda,会自动添加表别名,主表别名默认是 t ,非主表字段必须带别名查询 主表字段可以用lambda,会自动添加表别名,主表别名默认是 t ,非主表字段必须带别名查询
* leftJoin() rightJoin() innerJoin() 传sql片段 格式 (表 + 别名 + 关联条件) * leftJoin() rightJoin() innerJoin() 传sql片段 格式 (表 + 别名 + 关联条件)
* stringQuery() lambda查询转string查询 * stringQuery() lambda查询转string查询
* lambda() string查询转lambda查询 * lambda() string查询转lambda查询
* sql组装由mp完成,正常使用没有sql注入风险 * sql组装由mp完成,正常使用没有sql注入风险
### 分页查询 ### 分页查询
```java ```java
class test { class test {
@Resource @Resource
@ -110,32 +104,29 @@ class test {
void testJoin() { void testJoin() {
IPage<UserDTO> page = userMapper.selectJoinPage(new Page<>(1, 10), UserDTO.class, IPage<UserDTO> page = userMapper.selectJoinPage(new Page<>(1, 10), UserDTO.class,
new MyLambdaQuery<UserDO>() new MyLambdaQuery<UserDO>()
.selectAll(UserDO.class) .selectAll(UserDO.class)
.select("addr.tel", "addr.address") .select("addr.tel", "addr.address")
.select("a.province") .select("a.province")
.leftJoin("user_address addr on t.id = addr.user_id") .leftJoin("user_address addr on t.id = addr.user_id")
.rightJoin("area a on addr.area_id = a.id")); .rightJoin("area a on addr.area_id = a.id"));
} }
} }
``` ```
对应sql 对应sql
```sql ```sql
SELECT SELECT t.id,
t.id, t.name,
t.name, t.sex,
t.sex, t.head_img,
t.head_img, addr.tel,
addr.tel, addr.address,
addr.address, a.province
a.province FROM user t
FROM LEFT JOIN user_address addr on t.id = addr.user_id
user t RIGHT JOIN area a on addr.area_id = a.id LIMIT ?,?
LEFT JOIN user_address addr on t.id = addr.user_id
RIGHT JOIN area a on addr.area_id = a.id
LIMIT ?,?
``` ```
### 还可以这么操作,但不建议 ### 还可以这么操作,但不建议
@ -147,21 +138,21 @@ class test {
void testJoin() { void testJoin() {
List<UserDTO> list = userMapper.selectJoinList(UserDTO.class, List<UserDTO> list = userMapper.selectJoinList(UserDTO.class,
new MyLambdaQuery<UserDO>() new MyLambdaQuery<UserDO>()
.selectAll(UserDO.class) .selectAll(UserDO.class)
.select("addr.tel", "addr.address") .select("addr.tel", "addr.address")
//行列转换 //行列转换
.select("CASE t.sex WHEN '男' THEN '1' ELSE '0' END AS sex") .select("CASE t.sex WHEN '男' THEN '1' ELSE '0' END AS sex")
//求和函数 //求和函数
.select("sum(a.province) as province") .select("sum(a.province) as province")
//自定义数据集 //自定义数据集
.leftJoin("(select * from user_address) addr on t.id = addr.user_id") .leftJoin("(select * from user_address) addr on t.id = addr.user_id")
.rightJoin("area a on addr.area_id = a.id") .rightJoin("area a on addr.area_id = a.id")
.eq(true, UserDO::getId, 1) .eq(true, UserDO::getId, 1)
.stringQuery() .stringQuery()
.like(true, "addr.tel", "1") .like(true, "addr.tel", "1")
.le(true, "a.province", "1") .le(true, "a.province", "1")
.orderByDesc("addr.id")); .orderByDesc("addr.id"));
} }
} }
``` ```
@ -169,23 +160,21 @@ class test {
对应sql 对应sql
```sql ```sql
SELECT SELECT t.id,
t.id, t.name,
t.name, t.sex,
t.sex, t.head_img,
t.head_img, addr.tel,
addr.tel, addr.address,
addr.address, CASE t.sex WHEN '男' THEN '1' ELSE '0' END AS sex,
CASE t.sex WHEN '男' THEN '1' ELSE '0' END AS sex, sum(a.province) as province
sum(a.province) as province FROM user t
FROM LEFT JOIN (select * from user_address) addr on t.id = addr.user_id
user t RIGHT JOIN area a on addr.area_id = a.id
LEFT JOIN (select * from user_address) addr on t.id = addr.user_id
RIGHT JOIN area a on addr.area_id = a.id
WHERE ( WHERE (
t.id = ? t.id = ?
AND addr.tel LIKE ? AND addr.tel LIKE ?
AND a.province <= ?) AND a.province <= ?)
ORDER BY addr.id DESC ORDER BY addr.id DESC
``` ```
@ -201,12 +190,17 @@ class test {
private UserMapper userMapper; private UserMapper userMapper;
void testJoin() { void testJoin() {
List<UserDTO> list = userMapper.selectJoinList(UserDTO.class, new MyLambdaQueryWrapper<UserEntity>() List<UserDTO> list = userMapper.selectJoinList(UserDTO.class,
.selectAll(UserEntity.class) new MyLambdaQueryWrapper<UserDO>()
.leftJoin(UserEntity::getId, UserAddressEntity::getUserId, .selectAll(UserDO.class)
r1 -> r1.select(UserAddressEntity::getAddress) .select(UserAddressDO::getTel)
.leftJoin(UserAddressEntity::getAreaId, AreaEntity::getId, .selectAs(UserAddressDO::getAddress, UserDTO::getUserAddress)
r2 -> r2.select(AreaEntity::getProvince)))); .select(AreaDO::getProvince, AreaDO::getCity)
.leftJoin(UserAddressDO.class, UserAddressDO::getUserId, UserDO::getId)
.leftJoin(AreaDO.class, AreaDO::getId, UserAddressDO::getAreaId)
.eq(true, UserDO::getId, 1)
.like(true, UserAddressDO::getTel, "1")
.gt(true, UserDO::getId, 5));
} }
} }
``` ```
@ -214,98 +208,71 @@ class test {
对应sql 对应sql
```sql ```sql
SELECT t0.name, SELECT user.id,
t0.sex, user.name,
t0.head_img, user.sex,
t0.id, user.head_img,
t1.address, user_address.tel,
t2.province user_address.address AS userAddress,
FROM user t0 area.province,
LEFT JOIN user_address t1 ON t0.id = t1.user_id area.city
LEFT JOIN area t2 ON t1.area_id = t2.id FROM user
``` LEFT JOIN user_address ON user_address.user_id = user.id
LEFT JOIN area ON area.id = user_address.area_id
sql -> 伪代码
```java
class test {
void testJoin() {
List<UserDTO> list = userMapper.selectJoinList(UserDTO.class, new MyLambdaQueryWrapper<user表>()
.selectAll(user表实体类.class)//查询user表全部字段
.leftJoin(user表on字段, user_address表on字段,
user_address表对象 -> user_address表对象
.select(user_address表address字段)
.leftJoin(user_address表表的on字段, area表的on字段,
area表对象 -> area表对象.select(area表的province字段))));
}
}
```
#### 字段别名,查询字段别名 head_img as userHeadImg
```java
class test {
@Resource
private UserMapper userMapper;
void testJoin() {
List<UserDTO> list = userMapper.selectJoinList(UserDTO.class, new MyLambdaQueryWrapper<UserEntity>()
.as(UserEntity::getHeadImg, UserDTO::getUserHeadImg)
.leftJoin(UserEntity::getId, UserAddressEntity::getUserId,
right -> right.select(UserAddressEntity::getAddress, UserAddressEntity::getTel)));
}
}
```
对应sql
```sql
SELECT t0.head_img AS userHeadImg,
t1.address,
t1.tel
FROM user t0
LEFT JOIN user_address t1 ON t0.id = t1.user_id
```
#### 左连接 leftJoin(UserEntity::getId,UserAddressEntity::getUserId,right -> right)
前连个参数是两个表的连接条件:
user left join user_address on user.id = User_address.user_id
第三个参数是右表wrapper对象,可以继续使用,以上方法.
#### 条件查询
```java
class test {
@Resource
private UserMapper userMapper;
void testJoin() {
List<UserDTO> list = userMapper.selectJoinList(UserDTO.class, new MyLambdaQueryWrapper<UserEntity>()
.selectAll(UserEntity.class)
.leftJoin(UserEntity::getId, UserAddressEntity::getUserId,
right -> right.select(UserAddressEntity::getAddress, UserAddressEntity::getTel))
.eq(true, UserEntity::getId, 1)
.like(UserAddressEntity::getTel, "1")
.eq(UserEntity::getId, UserAddressEntity::getUserId));
}
}
```
对应sql
```sql
SELECT t0.name,
t0.sex,
t0.head_img,
t0.id,
t1.address,
t1.tel
FROM user t0
LEFT JOIN user_address t1 ON t0.id = t1.user_id
WHERE ( WHERE (
t0.id = ? user.id = ?
AND t1.tel LIKE ? AND user_address.tel LIKE ?
AND t0.id = t1.user_id) AND user.id > ?)
``` ```
说明:
* UserDTO.class 查询结果返回类(resultType)
* selectAll() 查询指定实体类的全部字段
* select() 查询指定的字段,支持可变参数,同意个select只能查询相同表的字段
故将UserAddressDO和AreaDO分开为连个select
* selectAs() 字段别名查询,用于数据库字段与业务实体类属性名不一致时使用
* leftJoin() 参数说明
第一个参数:参与连表的实体类class
第二个参数数:连表的ON字段,这个属性必须是第一个参数实体类的属性
第三个参数:参与连表的另一个实体类属性
* 条件查询,可以查询主表以及参与连接的所有表的字段,全部调用mp原生的方法,正常使用没有sql注入风险
#### 分页查询
```java
class test {
@Resource
private UserMapper userMapper;
void testJoin() {
IPage<UserDTO> iPage = userMapper.selectJoinPage(new Page<>(2, 10), UserDTO.class,
new MyLambdaQueryWrapper<UserDO>()
.selectAll(UserDO.class)
.select(UserAddressDO::getTel)
.selectAs(UserAddressDO::getAddress, UserDTO::getUserAddress)
.select(AreaDO::getProvince, AreaDO::getCity)
.leftJoin(UserAddressDO.class, UserAddressDO::getUserId, UserDO::getId)
.leftJoin(AreaDO.class, AreaDO::getId, UserAddressDO::getAreaId));
}
}
```
对应sql
```mysql
SELECT user.id,
user.name,
user.sex,
user.head_img,
user_address.tel,
user_address.address AS userAddress,
area.province,
area.city
FROM user
LEFT JOIN user_address ON user_address.user_id = user.id
LEFT JOIN area ON area.id = user_address.area_id
LIMIT ?,?
```

6
src/main/java/com/github/mybatisplus/wrapper/MyAbstractLambdaWrapper.java
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@ -14,6 +14,7 @@ import org.apache.ibatis.reflection.property.PropertyNamer;
import java.util.Arrays; import java.util.Arrays;
import java.util.HashMap; import java.util.HashMap;
import java.util.Map; import java.util.Map;
import java.util.Objects;
import static java.util.stream.Collectors.joining; import static java.util.stream.Collectors.joining;
@ -93,8 +94,9 @@ public abstract class MyAbstractLambdaWrapper<T, Children extends MyAbstractLamb
private ColumnCache getColumnCache(String fieldName, Class<?> lambdaClass) { private ColumnCache getColumnCache(String fieldName, Class<?> lambdaClass) {
ColumnCache columnCache = columnMap.get(LambdaUtils.formatKey(fieldName)); ColumnCache columnCache = columnMap.get(LambdaUtils.formatKey(fieldName));
Assert.notNull(columnCache, "can not find lambda cache for this property [%s] of entity [%s]", if (Objects.isNull(columnCache)) {
fieldName, lambdaClass.getName()); columnCache = new ColumnCache(fieldName, null);
}
return columnCache; return columnCache;
} }

10
src/main/java/com/github/mybatisplus/wrapper/MyLambdaQueryWrapper.java
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@ -118,10 +118,20 @@ public class MyLambdaQueryWrapper<T> extends MyAbstractLambdaWrapper<T, MyLambda
public final <S, X> MyLambdaQueryWrapper<T> selectAs(SFunction<S, ?> columns, SFunction<X, ?> alias) { public final <S, X> MyLambdaQueryWrapper<T> selectAs(SFunction<S, ?> columns, SFunction<X, ?> alias) {
Class<S> clazz = MyLambdaUtils.getEntityClass(columns); Class<S> clazz = MyLambdaUtils.getEntityClass(columns);
TableInfo info = TableInfoHelper.getTableInfo(clazz); TableInfo info = TableInfoHelper.getTableInfo(clazz);
Assert.notNull(info, "table can not be find for lambda");
selectColumns.add(new SelectColumn(clazz, info.getTableName(), MyLambdaUtils.getColumn(columns), MyLambdaUtils.getName(alias))); selectColumns.add(new SelectColumn(clazz, info.getTableName(), MyLambdaUtils.getColumn(columns), MyLambdaUtils.getName(alias)));
return typedThis; return typedThis;
} }
public final MyLambdaQueryWrapper<T> selectAll(Class<?> clazz) {
TableInfo info = TableInfoHelper.getTableInfo(clazz);
Assert.notNull(info, "table can not be find -> %s", clazz);
selectColumns.add(new SelectColumn(clazz, info.getTableName(), info.getKeyColumn(), null));
info.getFieldList().forEach(c ->
selectColumns.add(new SelectColumn(clazz, info.getTableName(), c.getColumn(), null)));
return typedThis;
}
@Override @Override
public String getSqlSelect() { public String getSqlSelect() {
if (StringUtils.isBlank(sqlSelect.getStringValue())) { if (StringUtils.isBlank(sqlSelect.getStringValue())) {