mybatis-plus中wrapper的用法（详细）

向右看齐 2022-09-10 03:15 497阅读 0赞

用到了wrapper，整理资料记录一下，以备后续复习。

**目录------------（可点击相应目录直接跳转）**

一、条件构造器关系介绍

条件构造器关系介绍 ：

wapper介绍 ：

二、项目实例

1、根据主键或者简单的查询条件进行查询

2、MyBatis-Plus还提供了Wrapper条件构造器，具体使用看如下代码：

三、具体使用操作

1、ge、gt、le、lt、isNull、isNotNull

2、eq、ne

3、between、notBetween

4、allEq

5、like、notLike、likeLeft、likeRight

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

7、or、and

8、嵌套or、嵌套and

9、orderBy、orderByDesc、orderByAsc

10、last

11、指定要查询的列

12、set、setSql

--------------------

## 一、条件构造器关系介绍 ##

![watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBA5Lme5Yqb6ams5omO572X44Gu6buO5piO_size_20_color_FFFFFF_t_70_g_se_x_16][]

### **条件构造器关系介绍 ：** ###

上图绿色框为抽象类abstract  
蓝色框为正常class类，可new对象  
黄色箭头指向为父子类关系，箭头指向为父类

###    **wapper介绍 ：** ###

Wrapper ： 条件构造抽象类，最顶端父类

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

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

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

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

LambdaQueryWrapper ：看名称也能明白就是用于Lambda语法使用的查询Wrapper

LambdaUpdateWrapper ： Lambda 更新封装Wrapper

## 二、项目实例 ##

![watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBA5Lme5Yqb6ams5omO572X44Gu6buO5piO_size_20_color_FFFFFF_t_70_g_se_x_16 1][]

### **1、根据主键或者简单的查询条件进行查询** ###

/**
 * 通过单个ID主键进行查询
 */
 @Test
 public void selectById() {
 User user = userMapper.selectById(1094592041087729666L);
 System.out.println(user);
 }
 
 /**
 * 通过多个ID主键查询
 */
 @Test
 public void selectByList() {
 List<Long> longs = Arrays.asList(1094592041087729666L, 1094590409767661570L);
 List<User> users = userMapper.selectBatchIds(longs);
 users.forEach(System.out::println);
 }
 
 /**
 * 通过Map参数进行查询
 */
 @Test
 public void selectByMap() {
 Map<String, Object> params = new HashMap<>();
 params.put("name", "张雨琪");
 List<User> users = userMapper.selectByMap(params);
 users.forEach(System.out::println);
 }

### 2、MyBatis-Plus还提供了Wrapper条件构造器，具体使用看如下代码： ###

/**
 * 名字包含雨并且年龄小于40
 * 
 * WHERE name LIKE '%雨%' AND age < 40
 */
 @Test
 public void selectByWrapperOne() {
 QueryWrapper<User> wrapper = new QueryWrapper();
 wrapper.like("name", "雨").lt("age", 40);
 List<User> users = userMapper.selectList(wrapper);
 users.forEach(System.out::println);
 }
 
 /**
 * 名字包含雨
 * 年龄大于20小于40
 * 邮箱不能为空
 * 
 * WHERE name LIKE '%雨%' AND age BETWEEN 20 AND 40 AND email IS NOT NULL
 */
 @Test
 public void selectByWrapperTwo() {
 QueryWrapper<User> wrapper = Wrappers.query();
 wrapper.like("name", "雨").between("age", 20, 40).isNotNull("email");
 List<User> users = userMapper.selectList(wrapper);
 users.forEach(System.out::println);
 }
 
 /**
 * 名字为王性
 * 或者年龄大于等于25
 * 按照年龄降序排序，年龄相同按照id升序排序
 * 
 * WHERE name LIKE '王%' OR age >= 25 ORDER BY age DESC , id ASC
 */
 @Test
 public void selectByWrapperThree() {
 QueryWrapper<User> wrapper = Wrappers.query();
 wrapper.likeRight("name", "王").or()
 .ge("age", 25).orderByDesc("age").orderByAsc("id");
 List<User> users = userMapper.selectList(wrapper);
 users.forEach(System.out::println);
 }
 
 /**
 * 查询创建时间为2019年2月14
 * 并且上级领导姓王
 * 
 * WHERE date_format(create_time,'%Y-%m-%d') = '2019-02-14' AND manager_id IN (select id from user where name like '王%')
 */
 @Test
 public void selectByWrapperFour() {
 QueryWrapper<User> wrapper = Wrappers.query();
 wrapper.apply("date_format(create_time,'%Y-%m-%d') = {0}", "2019-02-14")
 .inSql("manager_id", "select id from user where name like '王%'");
 List<User> users = userMapper.selectList(wrapper);
 users.forEach(System.out::println);
 }
 
 /**
 * 查询王姓
 * 并且年龄小于40或者邮箱不为空
 * 
 * WHERE name LIKE '王%' AND ( age < 40 OR email IS NOT NULL )
 */
 @Test
 public void selectByWrapperFive() {
 QueryWrapper<User> wrapper = Wrappers.query();
 wrapper.likeRight("name", "王").and(qw -> qw.lt("age", 40).or().isNotNull("email"));
 List<User> users = userMapper.selectList(wrapper);
 users.forEach(System.out::println);
 }
 
 /**
 * 查询王姓
 * 并且年龄大于20 、年龄小于40、邮箱不能为空
 * 
 * WHERE name LIKE ? OR ( age BETWEEN ? AND ? AND email IS NOT NULL )
 */
 @Test
 public void selectByWrapperSix() {
 QueryWrapper<User> wrapper = Wrappers.query();
 wrapper.likeRight("name", "王").or(
 qw -> qw.between("age", 20, 40).isNotNull("email")
 );
 List<User> users = userMapper.selectList(wrapper);
 users.forEach(System.out::println);
 }
 
 /**
 * (年龄小于40或者邮箱不为空) 并且名字姓王
 * WHERE ( age < 40 OR email IS NOT NULL ) AND name LIKE '王%'
 */
 @Test
 public void selectByWrapperSeven() {
 QueryWrapper<User> wrapper = Wrappers.query();
 wrapper.nested(qw -> qw.lt("age", 40).or().isNotNull("email"))
 .likeRight("name", "王");
 List<User> users = userMapper.selectList(wrapper);
 users.forEach(System.out::println);
 }
 
 /**
 * 查询年龄为30、31、32
 * WHERE age IN (?,?,?)
 */
 @Test
 public void selectByWrapperEight() {
 QueryWrapper<User> wrapper = Wrappers.query();
 wrapper.in("age", Arrays.asList(30, 31, 32));
 List<User> users = userMapper.selectList(wrapper);
 users.forEach(System.out::println);
 }
 
 /**
 * 查询一条数据
 * limit 1
 */
 @Test
 public void selectByWrapperNine() {
 QueryWrapper<User> wrapper = Wrappers.query();
 wrapper.in("age", Arrays.asList(30, 31, 32)).last("limit 1");
 List<User> users = userMapper.selectList(wrapper);
 users.forEach(System.out::println);
 }

## 三、具体使用操作 ##

**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);
 }

###    **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);9
 
 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** ###

in、notIn：

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

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 ?

\-------------------------------------------------------------------------------------以下无正文-------------------

参考文档

1、[https://blog.csdn.net/m0\_37034294/article/details/82917234][https_blog.csdn.net_m0_37034294_article_details_82917234]

2、https://blog.csdn.net/kepengs/article/details/112345870

3、[https://blog.csdn.net/weixin\_39615889/article/details/107086931][https_blog.csdn.net_weixin_39615889_article_details_107086931]

4、[https://blog.csdn.net/weixin\_38111957/article/details/91447509][https_blog.csdn.net_weixin_38111957_article_details_91447509]

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[https_blog.csdn.net_m0_37034294_article_details_82917234]: https://blog.csdn.net/m0_37034294/article/details/82917234
[https_blog.csdn.net_weixin_39615889_article_details_107086931]: https://blog.csdn.net/weixin_39615889/article/details/107086931
[https_blog.csdn.net_weixin_38111957_article_details_91447509]: https://blog.csdn.net/weixin_38111957/article/details/91447509