day01MyBatisPlus条件构造器(04)

一、wapper介绍 

 

1）Wrapper : 条件构造抽象类，最顶端父类

2） AbstractWrapper: 用于查询条件封装，生成 sql 的 where 条件

3）QueryWrapper: Entity 对象封装操作类，不是用lambda语法

4）UpdateWrapper: Update 条件封装，用于Entity对象更新操作

5）AbstractLambdaWrapper: Lambda 语法使用 Wrapper统一处理解析 lambda 获取 column。

6） LambdaQueryWrapper:用于Lambda语法使用的查询Wrapper

7）  LambdaUpdateWrapper: Lambda 更新封装Wrapper

 

 @RunWith(SpringRunner.class)

@SpringBootTest

public class QueryWrapperTests {

        @Autowired

    private UserMapper userMapper;

}

二、AbstractWrapper

注意：以下条件构造器的方法入参中的 column 均表示数据库字段

1、ge、gt、le、lt、isNull、isNotNull

 

@Test

public void testDelete() {

​    QueryWrapper<User> queryWrapper = new QueryWrapper<>();

    queryWrapper

        .isNull("name")

        .ge("age", 12)

        .isNotNull("email");

    int result = userMapper.delete(queryWrapper);

    System.out.println("delete return count = " + result);

}

SQL：UPDATE user SET deleted=1 WHERE deleted=0 AND name IS NULL AND age >= ? AND email IS NOT NULL

 

2、eq、ne

注意：seletOne返回的是一条实体记录，当出现多条时会报错 

@Test

public void testSelectOne() {

​    QueryWrapper<User> queryWrapper = new QueryWrapper<>();

    queryWrapper.eq("name", "Tom");

​    User user = userMapper.selectOne(queryWrapper);

    System.out.println(user);

}
SELECT id,name,age,email,create_time,update_time,deleted,version FROM user WHERE deleted=0 AND name = ?

3、between、notBetween

包含大小边界

@Test

public void testSelectCount() {

​    QueryWrapper<User> queryWrapper = new QueryWrapper<>();

    queryWrapper.between("age", 20, 30);

​    Integer count = userMapper.selectCount(queryWrapper);

    System.out.println(count);

}
SELECT COUNT(1) FROM user WHERE deleted=0 AND age BETWEEN ? AND ?

4、allEq

 

@Test

public void testSelectList() {

​    QueryWrapper<User> queryWrapper = new QueryWrapper<>();

    Map<String, Object> map = new HashMap<>();

    map.put("id", 2);

    map.put("name", "Jack");

    map.put("age", 20);

​    queryWrapper.allEq(map);

    List<User> users = userMapper.selectList(queryWrapper);

​    users.forEach(System.out::println);

}
SELECT id,name,age,email,create_time,update_time,deleted,version 

FROM user WHERE deleted=0 AND name = ? AND id = ? AND age = ?

5、like、notLike、likeLeft、likeRight

selectMaps返回Map集合列表

 @Test

public void testSelectMaps() {

​    QueryWrapper<User> queryWrapper = new QueryWrapper<>();

    queryWrapper

        .notLike("name", "e")

        .likeRight("email", "t");

​    List<Map<String, Object>> maps = userMapper.selectMaps(queryWrapper);//返回值是Map列表

    maps.forEach(System.out::println);

}
SELECT id,name,age,email,create_time,update_time,deleted,version 

FROM user WHERE deleted=0 AND name NOT LIKE ? AND email LIKE ?

 

6、in、notIn、inSql、notinSql、exists、notExists

(1)in、notIn：

notIn("age",{1,2,3})--->age not in (1,2,3)

notIn("age", 1, 2, 3)--->age not in (1,2,3)

(2)inSql、notinSql：可以实现子查询

例: inSql("age", "1,2,3,4,5,6")--->age in (1,2,3,4,5,6)

例: inSql("id", "select id from table where id < 3")--->id in (select id from table where id < 3)

 

@Test

public void testSelectObjs() {

​    QueryWrapper<User> queryWrapper = new QueryWrapper<>();

    //queryWrapper.in("id", 1, 2, 3);

    queryWrapper.inSql("id", "select id from user where id < 3");

​    List<Object> objects = userMapper.selectObjs(queryWrapper);//返回值是Object列表

    objects.forEach(System.out::println);

}
SELECT id,name,age,email,create_time,update_time,deleted,version 

FROM user WHERE deleted=0 AND id IN (select id from user where id < 3)

7、or、and

注意：这里使用的是 UpdateWrapper 

不调用or则默认为使用 and 连

@Test

public void testUpdate1() {

​    //修改值

    User user = new User();

    user.setAge(99);

    user.setName("Andy");

​    //修改条件

    UpdateWrapper<User> userUpdateWrapper = new UpdateWrapper<>();

    userUpdateWrapper

        .like("name", "h")

        .or()

        .between("age", 20, 30);

​    int result = userMapper.update(user, userUpdateWrapper);

​    System.out.println(result);

}
UPDATE user SET name=?, age=?, update_time=? WHERE deleted=0 AND name LIKE ? OR age BETWEEN ? AND ?

8、嵌套or、嵌套and

这里使用了lambda表达式，or中的表达式最后翻译成sql时会被加上圆括号

 

@Test

public void testUpdate2() {

​    //修改值

    User user = new User();

    user.setAge(99);

    user.setName("Andy");

​    //修改条件

    UpdateWrapper<User> userUpdateWrapper = new UpdateWrapper<>();

    userUpdateWrapper

        .like("name", "h")

        .or(i -> i.eq("name", "李白").ne("age", 20));

​    int result = userMapper.update(user, userUpdateWrapper);

​    System.out.println(result);

}
UPDATE user SET name=?, age=?, update_time=? 

WHERE deleted=0 AND name LIKE ? 

OR ( name = ? AND age <> ? )

9、orderBy、orderByDesc、orderByAsc

@Test

public void testSelectListOrderBy() {

​    QueryWrapper<User> queryWrapper = new QueryWrapper<>();

    queryWrapper.orderByDesc("id");

​    List<User> users = userMapper.selectList(queryWrapper);

    users.forEach(System.out::println);

}
SELECT id,name,age,email,create_time,update_time,deleted,version 

FROM user WHERE deleted=0 ORDER BY id DESC

10、last

直接拼接到 sql 的最后

注意：只能调用一次,多次调用以最后一次为准 有sql注入的风险,请谨慎使用

@Test

public void testSelectListLast() {

​    QueryWrapper<User> queryWrapper = new QueryWrapper<>();

    queryWrapper.last("limit 1");

​    List<User> users = userMapper.selectList(queryWrapper);

    users.forEach(System.out::println);

}
SELECT id,name,age,email,create_time,update_time,deleted,version 

FROM user WHERE deleted=0 limit 1

11、指定要查询的列 

@Test

public void testSelectListColumn() {

​    QueryWrapper<User> queryWrapper = new QueryWrapper<>();

    queryWrapper.select("id", "name", "age");

​    List<User> users = userMapper.selectList(queryWrapper);

    users.forEach(System.out::println);

}
SELECT id,name,age FROM user WHERE deleted=0  

12、set、setSql

最终的sql会合并 user.setAge()，以及 userUpdateWrapper.set()  和 setSql() 中 的字段 

@Test

public void testUpdateSet() {

​

    //修改值

    User user = new User();

    user.setAge(99);

​    //修改条件

    UpdateWrapper<User> userUpdateWrapper = new UpdateWrapper<>();

    userUpdateWrapper

        .like("name", "h")

        .set("name", "老李头")//除了可以查询还可以使用set设置修改的字段

        .setSql(" email = '123@qq.com'");//可以有子查询

​    int result = userMapper.update(user, userUpdateWrapper);

}
UPDATE user SET age=?, update_time=?, name=?, email = '123@qq.com' WHERE deleted=0 AND name LIKE ?

13、MP实现条件查询

13.1、MP条件查询构造器

 

13.2、常用方法

1）ge gt le lt

2）eq ne

3) between

4)like

5)orderByDesc

6)select

13.3、测试

//根据条件构造器查询
@Test
public void estSelect(){
    QueryWrapper<User> wrapper = new QueryWrapper<>();
    //ge gt le lt
    //wrapper.ge("age",20);
    //eq ne
    //wrapper.eq("name","zhang3");
    //between
    //wrapper.between("age",20,33);
    //like
    //wrapper.like("name","J");
    //orderByDesc
    wrapper.orderByDesc("age");
    //select
    wrapper.select("name","age");

    List<User> users = userMapper.selectList(wrapper);
    users.forEach(System.out::println);
}

一、wapper介绍 

 

1）Wrapper : 条件构造抽象类，最顶端父类

2） AbstractWrapper: 用于查询条件封装，生成 sql 的 where 条件

3）QueryWrapper: Entity 对象封装操作类，不是用lambda语法

4）UpdateWrapper: Update 条件封装，用于Entity对象更新操作

5）AbstractLambdaWrapper: Lambda 语法使用 Wrapper统一处理解析 lambda 获取 column。

6） LambdaQueryWrapper:用于Lambda语法使用的查询Wrapper

7）  LambdaUpdateWrapper: Lambda 更新封装Wrapper

 

 @RunWith(SpringRunner.class)

@SpringBootTest

public class QueryWrapperTests {

        @Autowired

    private UserMapper userMapper;

}

二、AbstractWrapper

注意：以下条件构造器的方法入参中的 column 均表示数据库字段

1、ge、gt、le、lt、isNull、isNotNull

 

@Test

public void testDelete() {

​    QueryWrapper<User> queryWrapper = new QueryWrapper<>();

    queryWrapper

        .isNull("name")

        .ge("age", 12)

        .isNotNull("email");

    int result = userMapper.delete(queryWrapper);

    System.out.println("delete return count = " + result);

}

SQL：UPDATE user SET deleted=1 WHERE deleted=0 AND name IS NULL AND age >= ? AND email IS NOT NULL

 

2、eq、ne

注意：seletOne返回的是一条实体记录，当出现多条时会报错

 @Test

public void testSelectOne() {

​    QueryWrapper<User> queryWrapper = new QueryWrapper<>();

    queryWrapper.eq("name", "Tom");

​    User user = userMapper.selectOne(queryWrapper);

    System.out.println(user);

}

SELECT id,name,age,email,create_time,update_time,deleted,version FROM user WHERE deleted=0 AND name = ? 

 

3、between、notBetween

包含大小边界

 @Test

public void testSelectCount() {

​    QueryWrapper<User> queryWrapper = new QueryWrapper<>();

    queryWrapper.between("age", 20, 30);

​    Integer count = userMapper.selectCount(queryWrapper);

    System.out.println(count);

}

SELECT COUNT(1) FROM user WHERE deleted=0 AND age BETWEEN ? AND ? 

 

4、allEq

 @Test

public void testSelectList() {

​    QueryWrapper<User> queryWrapper = new QueryWrapper<>();

    Map<String, Object> map = new HashMap<>();

    map.put("id", 2);

    map.put("name", "Jack");

    map.put("age", 20);

​    queryWrapper.allEq(map);

    List<User> users = userMapper.selectList(queryWrapper);

​    users.forEach(System.out::println);

}

SELECT id,name,age,email,create_time,update_time,deleted,version 

FROM user WHERE deleted=0 AND name = ? AND id = ? AND age = ? 

5、like、notLike、likeLeft、likeRight

selectMaps返回Map集合列表

 @Test

public void testSelectMaps() {

​    QueryWrapper<User> queryWrapper = new QueryWrapper<>();

    queryWrapper

        .notLike("name", "e")

        .likeRight("email", "t");

​    List<Map<String, Object>> maps = userMapper.selectMaps(queryWrapper);//返回值是Map列表

    maps.forEach(System.out::println);

}

SELECT id,name,age,email,create_time,update_time,deleted,version 

FROM user WHERE deleted=0 AND name NOT LIKE ? AND email LIKE ? 

 

6、in、notIn、inSql、notinSql、exists、notExists

(1)in、notIn：

notIn("age",{1,2,3})--->age not in (1,2,3)

notIn("age", 1, 2, 3)--->age not in (1,2,3)

(2)inSql、notinSql：可以实现子查询

例: inSql("age", "1,2,3,4,5,6")--->age in (1,2,3,4,5,6)

例: inSql("id", "select id from table where id < 3")--->id in (select id from table where id < 3)

 

@Test

public void testSelectObjs() {

​    QueryWrapper<User> queryWrapper = new QueryWrapper<>();

    //queryWrapper.in("id", 1, 2, 3);

    queryWrapper.inSql("id", "select id from user where id < 3");

​    List<Object> objects = userMapper.selectObjs(queryWrapper);//返回值是Object列表

    objects.forEach(System.out::println);

}

SELECT id,name,age,email,create_time,update_time,deleted,version 

FROM user WHERE deleted=0 AND id IN (select id from user where id < 3) 

 

7、or、and

注意：这里使用的是 UpdateWrapper 

不调用or则默认为使用 and 连

@Test

public void testUpdate1() {

​    //修改值

    User user = new User();

    user.setAge(99);

    user.setName("Andy");

​    //修改条件

    UpdateWrapper<User> userUpdateWrapper = new UpdateWrapper<>();

    userUpdateWrapper

        .like("name", "h")

        .or()

        .between("age", 20, 30);

​    int result = userMapper.update(user, userUpdateWrapper);

​    System.out.println(result);

}

UPDATE user SET name=?, age=?, update_time=? WHERE deleted=0 AND name LIKE ? OR age BETWEEN ? AND ?

 

8、嵌套or、嵌套and

这里使用了lambda表达式，or中的表达式最后翻译成sql时会被加上圆括号

 

@Test

public void testUpdate2() {

​    //修改值

    User user = new User();

    user.setAge(99);

    user.setName("Andy");

​    //修改条件

    UpdateWrapper<User> userUpdateWrapper = new UpdateWrapper<>();

    userUpdateWrapper

        .like("name", "h")

        .or(i -> i.eq("name", "李白").ne("age", 20));

​    int result = userMapper.update(user, userUpdateWrapper);

​    System.out.println(result);

}

UPDATE user SET name=?, age=?, update_time=? 

WHERE deleted=0 AND name LIKE ? 

OR ( name = ? AND age <> ? ) 

9、orderBy、orderByDesc、orderByAsc

 @Test

public void testSelectListOrderBy() {

​    QueryWrapper<User> queryWrapper = new QueryWrapper<>();

    queryWrapper.orderByDesc("id");

​    List<User> users = userMapper.selectList(queryWrapper);

    users.forEach(System.out::println);

}

SELECT id,name,age,email,create_time,update_time,deleted,version 

FROM user WHERE deleted=0 ORDER BY id DESC 

 

10、last

直接拼接到 sql 的最后

注意：只能调用一次,多次调用以最后一次为准 有sql注入的风险,请谨慎使用

 @Test

public void testSelectListLast() {

​    QueryWrapper<User> queryWrapper = new QueryWrapper<>();

    queryWrapper.last("limit 1");

​    List<User> users = userMapper.selectList(queryWrapper);

    users.forEach(System.out::println);

}

SELECT id,name,age,email,create_time,update_time,deleted,version 

FROM user WHERE deleted=0 limit 1 

11、指定要查询的列

 @Test

public void testSelectListColumn() {

​    QueryWrapper<User> queryWrapper = new QueryWrapper<>();

    queryWrapper.select("id", "name", "age");

​    List<User> users = userMapper.selectList(queryWrapper);

    users.forEach(System.out::println);

}

SELECT id,name,age FROM user WHERE deleted=0 

 

12、set、setSql

最终的sql会合并 user.setAge()，以及 userUpdateWrapper.set()  和 setSql() 中 的字段

 @Test

public void testUpdateSet() {

​

    //修改值

    User user = new User();

    user.setAge(99);

​    //修改条件

    UpdateWrapper<User> userUpdateWrapper = new UpdateWrapper<>();

    userUpdateWrapper

        .like("name", "h")

        .set("name", "老李头")//除了可以查询还可以使用set设置修改的字段

        .setSql(" email = '123@qq.com'");//可以有子查询

​    int result = userMapper.update(user, userUpdateWrapper);

}

UPDATE user SET age=?, update_time=?, name=?, email = '123@qq.com' WHERE deleted=0 AND name LIKE ? 

13、MP实现条件查询

1、MP条件查询构造器

 

2常用方法

1）ge gt le lt

2）eq ne

3) between

4)like

5)orderByDesc

6)select

3、测试

//根据条件构造器查询
@Test
public void estSelect(){
    QueryWrapper<User> wrapper = new QueryWrapper<>();
    //ge gt le lt
    //wrapper.ge("age",20);
    //eq ne
    //wrapper.eq("name","zhang3");
    //between
    //wrapper.between("age",20,33);
    //like
    //wrapper.like("name","J");
    //orderByDesc
    wrapper.orderByDesc("age");
    //select
    wrapper.select("name","age");

    List<User> users = userMapper.selectList(wrapper);
    users.forEach(System.out::println);
}

 

 

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原文地址：https://www.cnblogs.com/lvwuwa/p/14016009.html