springboot09-wapper

Wapper（条件构造器）

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

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

eq、ne

注意：seletOne返回的是一条实体记录，当出现多条时会报错```java

@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 = ?

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 ?
…其他方法边用边学