mybatisplus常用语法

pom配置

    
   
      com.baomidou
      mybatis-plus-boot-starter
      3.5.3
    
    
      com.baomidou
      mybatis-plus
      3.5.3
    
    
    
      com.baomidou
      dynamic-datasource-spring-boot-starter
      3.3.2
    

1.User

@Data//lombok-get()、 set()、 toString()
/**
 * 1. @TableName： 解决实体类的名称与数据库中的表名不匹配的问题
 */
@TableName(value ="test_user_1")
public class User {

     /**
      * 1. @TableId：专门用在主键上的注解 :
      *        value：映射主键字段的名字，即数据库的列名 (不配置则一样/驼峰命名对应)
      *        type：设置主键类型、主键的生成策略
      *			    AUTO	数据库自增
      * 			NONE	MP set主键，雪花算法实现
      * 			INPUT	需要手动赋值
      * 			ASSIGN_ID	MP分配ID，Long、Integer、String
      * 			ASSIGN_UUID	分配UUID，String
      *
      * 2. 主键类型慎用基本数据类型（int），要使用其包装类(Integer)
      *        如int默认值为0，在mypatisplus的insert中，将不会使用算法生成id，直接使用默认值进行处理。如下：
      *             ==>  Preparing: INSERT INTO test_user ( id, name, age, desc ) VALUES ( ?, ?, ?, ? )
      *             ==> Parameters: 0(Integer), 张三03-30 11:50(String), 50(Integer), 插入[张三03-30 11:50](String)
      */
     @TableId(value = "id", type = IdType.AUTO)
     private Integer ids;


     private String name;

     private int age;

     /**
      * 1. @TableField：
      *        value： 解决实体类的字段名与数据库中的字段名不匹配的问题
      *        exist = false： 用来解决实体中存在，单数表中不存在的字段
      */
     @TableField(value = "description")
     private String descr;

     /**
      * 该字段在数据库中不存在
      */
     @TableField(exist = false)
     private String zth;
}

2.UserMapper

@Repository
@DS("master")//@DS 可以注解在方法上或类上，同时存在就近原则 方法上注解 优先于 类上注解。
public interface UserMapper extends BaseMapper {



}

3.CRUD

3.1. insert

User user = new User();
user.setName("张三"+ ToolsTime.getHHMM());
user.setAge(ToolsTime.getMM());
user.setDescr("插入["+user.getName()+"]");

int res = mapper.insert(user);
System.err.println("***[mybatisplus] 插入后的用户Id: "+user.getIds());
//1.插入后自动填充其id
//==>  Preparing: INSERT INTO test_user_1 ( name, age, description ) VALUES ( ?, ?, ? )
//==> Parameters: 张三03-30 15:05(String), 5(Integer), 插入[张三03-30 15:05](String)


user = new User();
user.setName("李四"+ ToolsTime.getHHMM());
mapper.insert(user);
//2.插入时，为null的属性，不插入
//==>  Preparing: INSERT INTO test_user_1 ( name, age ) VALUES ( ?, ? )
//==> Parameters: 李四15:07(String), 0(Integer)

3.2.update

User user = mapper.selectById(3);

//1. updateById
// ==>  Preparing: UPDATE test_user_1 SET name=?, age=?, description=? WHERE id=?
//==> Parameters: 张三(String), 18(Integer), 编辑(String), 1(Integer)
user.setDescr("编辑");
mapper.updateById(user);

//2. QueryWrapper
// ==>  Preparing:
//      UPDATE test_user_1
//          SET name=?,
//              age=?
//          WHERE (name = ?)
//==> Parameters: 李四update(String), 0(Integer), 李四(String)
QueryWrapper queryWrapper = new QueryWrapper<>();
queryWrapper.eq("name","李四");
user = new User();
user.setName("李四update");
mapper.update(user, queryWrapper);


//3.QueryWrapper
//==>  Preparing: UPDATE test_user_1 SET age=? WHERE (name = ?)
//==> Parameters: 0(Integer), 李四(String)
queryWrapper = new QueryWrapper<>();
queryWrapper.eq("name","李四");
mapper.update(new User(), queryWrapper);


//4.UpdateWrapper
//==>  Preparing: UPDATE test_user_1 SET age=? WHERE (name = ?)
//==> Parameters: 0(Integer), 李四(String)
UpdateWrapper uw  = new UpdateWrapper<>();
uw.eq("name","李四");
mapper.update(new User(), uw);


//5.QueryWrapper
//==>  Preparing: UPDATE test_user_1 SET age=?, description=? WHERE (name = ?)
//==> Parameters: 0(Integer), null, 李四(String)
uw  = new UpdateWrapper<>();
uw.eq("name","李四");
uw.set("description", null);
mapper.update(new User(), uw);




//6.不创建对象
// ==>  Preparing: UPDATE test_user_1 SET description=? WHERE (name = ?)
//==> Parameters: null, 李四(String)
uw  = new UpdateWrapper<>();
uw.eq("name","李四");
uw.set("description", null);
mapper.update(null, uw);

3.3.delete

User user = mapper.selectById(1);

//1. deleteById
// ==>  Preparing: DELETE FROM test_user_1 WHERE id=?
//==> Parameters: 1(Integer)
mapper.deleteById(user);

//2. delete(T , QueryWrapper)
// ==>  Preparing: DELETE FROM test_user_1 WHERE (name = ?)
//==> Parameters: 李四(String)
QueryWrapper queryWrapper = new QueryWrapper<>();
queryWrapper.eq("name","李四");
mapper.delete(queryWrapper);

//3. deleteBatchIds
// ==>  Preparing: DELETE FROM test_user_1 WHERE id IN ( ? , ? , ? )
//==> Parameters: 8(Integer), 9(Integer), 10(Integer)
mapper.deleteBatchIds(Arrays.asList(8, 9, 10));


//4. deleteByMap
// ==>  Preparing: DELETE FROM test_user_1 WHERE name = ? AND age = ?
//==> Parameters: 张三(String), 18(String)
HashMap map = new HashMap<>();
map.put("name", "张三");
map.put("age", "18");
int result = mapper.deleteByMap(map);

3.4.select

//1.插入101用户
User user = new User();
user.setIds(101);
user.setName("张三101");
user.setAge(ToolsTime.getMM());
user.setDescr("插入["+user.getName()+"]");
mapper.insert(user);

//2.selectById：通过id查询
//==>  Preparing: SELECT id AS ids,name,age,description AS descr FROM test_user_1 WHERE id=?
//==> Parameters: 101(Integer)
User u = mapper.selectById(101);
System.err.println("***[mybatisplus] selectById: "+u);

//3.selectOne：查询一条数据(多条则报错，org.apache.ibatis.exceptions.TooManyResultsException: Expected one result (or null) to be returned by selectOne(), but found: 4)
//==>  Preparing: SELECT id AS ids,name,age,description AS descr FROM test_user_1 WHERE (name = ?)
//==> Parameters: 张三101(String)
QueryWrapper wrapper = new QueryWrapper();
wrapper.eq("name", "张三101");
u = mapper.selectOne(wrapper);
System.err.println("***[mybatisplus] selectOne: "+u);


//4.selectList：查询数据
//==>  Preparing: SELECT id AS ids,name,age,description AS descr FROM test_user_1 WHERE (name = ?)
//==> Parameters: 张三(String)
wrapper = new QueryWrapper();
wrapper.eq("name", "张三");
List list = mapper.selectList(wrapper);
System.err.println("***[mybatisplus] selectList: "+list);


//5.selectCount: 查询总数
//==>  Preparing: SELECT COUNT( * ) AS total FROM test_user_1 WHERE (name = ?)
//==> Parameters: 张三(String)
Long num = mapper.selectCount(wrapper);
System.err.println("***[mybatisplus] selectCount: "+num);

System.err.println("----------------------------------baseMapper 自带分页-------------------------------------------------------");
//6.selectPage： 分页查询(需在MybatisPlusConfig中配置分页插件)
// ==>  Preparing: SELECT COUNT(*) AS total FROM test_user_1
// ==> Parameters:
// ==>  Preparing: SELECT id AS ids, name, age, description AS descr FROM test_user_1 ORDER BY age ASC LIMIT ?,?
// ==> Parameters: 3(Long), 3(Long)
Page page = new Page<>(2, 3);
page.addOrder(OrderItem.asc("age"));
mapper.selectPage(page, null);
System.err.println("***[mybatisplus] 数据list: "+page.getRecords());
System.err.println("***[mybatisplus] 总条数: "+page.getTotal());
System.err.println("***[mybatisplus] 当前页码: "+page.getCurrent());
System.err.println("***[mybatisplus] 每页数量: "+page.getSize());
System.err.println("***[mybatisplus] 总页数: "+page.getPages());

System.err.println("----------------------------------json 正反序列化-------------------------------------------------------");
String json = JSON.toJSONString(page);
System.err.println(json);
Page page1 = JSON.parseObject(json, new TypeReference>() {});
System.err.println(page1);

4.MybatisPlusConfig

@Configuration
@MapperScan("org.example.mapper")
public class MybatisPlusConfig {

    public final static String dbName = "dbName";

    /**
     * //1.分页插件
     * @return
     */
    @Bean
    public MybatisPlusInterceptor mybatisPlusInterceptor2(){
        MybatisPlusInterceptor mybatisPlusInterceptor = new MybatisPlusInterceptor();
        mybatisPlusInterceptor.addInnerInterceptor(new PaginationInnerInterceptor());
        return mybatisPlusInterceptor;
    }

}

5.其他查询

/**
     * 查询： 大于等于、大于、小于等于、小于、为空、非空，等于，不等于
     * ge、gt、le、lt、isNull、isNotNull
     */
    @Test
    public void select1() {
        QueryWrapper wrapper = new QueryWrapper<>();

        //==>  Preparing: SELECT id AS ids,name,age,description AS descr FROM test_user_1 WHERE (
        //  name IS NOT NULL AND
        //  msg IS NULL AND
        //  age >= ?
        //  AND description = ?
        //  AND msg <> ?)
        //==> Parameters: (String), test_user_1(String), (String)
        wrapper
                .isNotNull("name")  //不为空
                .isNull("msg")      //为空
                .ge("age", "")  //大于等于12
                .eq("description", "test_user_1") //等于
                .ne("msg", "")  //不等
            ;
        List list = mapper.selectList(wrapper);
        System.err.println("***[mybatisplus] selectList: "+list);
    }

    /**
     * 1、and-or连接
     * 2、排序： orderBy、orderByDesc、orderByAsc
     * 3、last 直接拼接到 sql 的最后
     * 4、查询特定的列
     */
    @Test
    public void select2() {
        QueryWrapper queryWrapper = new QueryWrapper<>();
        //1.默认and连接
        // ==>  Preparing: SELECT COUNT( * ) AS total FROM test_user_1 WHERE (age = ? AND name LIKE ?)
        //==> Parameters: 18(Integer), %张三%(String)
        queryWrapper.eq("age", 18).like("name","张三");
        Long res = mapper.selectCount(queryWrapper);
        System.err.println("***[mybatisplus] : "+res);

        //2.or连接
        // ==>  Preparing: SELECT COUNT( * ) AS total FROM test_user_1 WHERE (age = ? OR name = ?)
        //==> Parameters: 18(Integer), 张三(String)
        queryWrapper = new QueryWrapper<>();
        queryWrapper.eq("age", 18).or().eq("name","张三");
        mapper.selectCount(queryWrapper);
        System.err.println("***[mybatisplus] : "+res);


        //3.and-or连接
        // ==>  Preparing: SELECT COUNT( * ) AS total FROM test_user_1 WHERE (name = ? AND (age = ? OR msg IS NULL))
        //==> Parameters: 张三(String), 28(Integer)
        queryWrapper = new QueryWrapper<>();
        queryWrapper.eq("name","张三").and(
                wrapper -> wrapper.eq("age", 28).
                        or().isNull("msg")
        );
        mapper.selectCount(queryWrapper);
        System.err.println("***[mybatisplus] : "+res);

        //4.排序： orderBy、orderByDesc、orderByAsc
        // ==>  Preparing: SELECT id AS ids,name,age,description AS descr FROM test_user_1 ORDER BY age DESC,name ASC
        //==> Parameters:
        queryWrapper = new QueryWrapper<>();
        queryWrapper.orderByDesc("age").orderByAsc("name");
        List list = mapper.selectList(queryWrapper);
        System.err.println("***[mybatisplus] : "+list);

        //5.last 直接拼接到 sql 的最后
        // ==>  Preparing: SELECT id,name,description FROM test_user_1 limit 1
        //==> Parameters:
        queryWrapper = new QueryWrapper<>();
        queryWrapper.last("limit 1");
        //6.查询特定的列: 注意为数据库列
        queryWrapper.select("id", "name", "description");
        User user = mapper.selectOne(queryWrapper);
        System.err.println("***[mybatisplus] : "+user);

        //7.selectByMap
        // ==>  Preparing: SELECT id AS ids,name,age,description AS descr FROM test_user_1 WHERE name = ? AND age = ?
        //==> Parameters: 张三(String), 28(Integer)
        HashMap map = new HashMap<>();
        map.put("name", "张三");
        map.put("age", 28);
        List users = mapper.selectByMap(map);
        System.err.println("***[mybatisplus] : "+user);

        //8.max(id)
        //==>  Preparing: SELECT max(id) as ids FROM test_user_1
        QueryWrapper wrapper = new QueryWrapper<>();
        wrapper.select("max(id) as ids");
        user = mapper.selectOne(wrapper);
        System.err.println("***[mybatisplus] : "+user);
    }





    /**
     * 查询： between、notBetween 包含大小边界
     */
    @Test
    public void select3() {
        QueryWrapper queryWrapper = new QueryWrapper<>();
        //==>  Preparing: SELECT COUNT( * ) AS total FROM test_user_1 WHERE (age BETWEEN ? AND ?)
        //==> Parameters: 18(Integer), 20(Integer)
        queryWrapper.between("age", 18, 20);
        Long count = mapper.selectCount(queryWrapper);
        System.err.println(count);

    }


    /**
     * allEq
     */
    @Test
    public void select4() {
        QueryWrapper queryWrapper = new QueryWrapper<>();
        Map map = new HashMap<>();
        map.put("id", 2);
        map.put("name", "张三");
        map.put("age", 18);
        queryWrapper.allEq(map);
        //==>  Preparing: SELECT COUNT( * ) AS total FROM test_user_1 WHERE (name = ? AND id = ? AND age = ?)
        //==> Parameters: 张三(String), 2(Integer), 18(Integer)
        Long count = mapper.selectCount(queryWrapper);
        System.err.println(count);

    }


    /**
     * like、notLike、likeLeft、likeRight
     */
    @Test
    public void select5() {
        QueryWrapper queryWrapper = new QueryWrapper<>();
        queryWrapper
                .likeLeft("name", "三")
                .like("description", "test_user_1")
                .likeRight("msg", "test_user_1");
        //==>  Preparing: SELECT id AS ids,name,age,description AS descr FROM test_user_1 WHERE (name LIKE ? AND description LIKE ? AND msg LIKE ?)
        //==> Parameters: %三(String), %test_user_1%(String), test_user_1%(String)
        List> maps = mapper.selectMaps(queryWrapper);//返回值是Map列表
        maps.forEach(System.err::println);
    }


    /**
     * in、notIn、inSql、notinSql、exists、notExists
     *     notIn("age",{1,2,3})--->age not in (1,2,3)
     *     notIn("age", 1, 2, 3)--->age not in (1,2,3)
     */
    @Test
    public void select6() {

        QueryWrapper queryWrapper = new QueryWrapper<>();
        queryWrapper.in("age", 18,28,38);
        queryWrapper.inSql("id", "select id from test_user_1 where id < 5");
        queryWrapper.notIn("name", "joney","tom");

        //==>  Preparing: SELECT id AS ids,name,age,description AS descr FROM test_user_1
        //      WHERE (
        //          age IN (?,?,?) AND
        //          id IN (select id from test_user_1 where id < 5)
        //          AND name NOT IN (?,?)
        //      )
        //==> Parameters: 18(Integer), 28(Integer), 38(Integer), joney(String), tom(String)
        List