public void testAllEq(){  
  
    Map<String,Object> params = new HashMap<>();  
    params.put("name", "李四");  
    params.put("age", "20");  
    params.put("password", null);  
  
    QueryWrapper<User> wrapper = new QueryWrapper<>();  
    //SELECT id,user_name,name,age,email AS mail FROM tb_user WHERE password IS NULL AND name = ? AND age = ?  
    //wrapper.allEq(params);  
    
    //SELECT id,user_name,name,age,email AS mail FROM tb_user WHERE name = ? AND age = ?
    //wrapper.allEq(params, false);  
  
    //SELECT id,user_name,name,age,email AS mail FROM tb_user WHERE age = ?
    //wrapper.allEq((k, v) -> (k.equals("age") || k.equals("id")) , params);  
    
    //SELECT id,user_name,name,age,email AS mail FROM tb_user WHERE name = ? AND age = ?
    wrapper.allEq((k, v) -> (k.equals("age") || k.equals("id") || k.equals("name")) , params);  
  
    List<User> users = this.userMapper.selectList(wrapper);  
    for (User user : users) {  
        System.out.println(user);  
    }  
}

public void testLike(){  
    QueryWrapper<User> wrapper = new QueryWrapper<>();  
    // SELECT id,user_name,name,age,email AS mail FROM tb_user WHERE name LIKE ?  
    // 参数：%五(String)  
    wrapper.likeLeft("name", "五");  
  
    List<User> users = this.userMapper.selectList(wrapper);  
    for (User user : users) {  
        System.out.println(user);  
    }  
}

public void testOr(){  
    QueryWrapper<User> wrapper = new QueryWrapper<>();  
    // SELECT id,user_name,name,age,email AS mail FROM tb_user WHERE name = ? OR age = ?  
    wrapper.eq("name", "王五").or().eq("age", 21);  
  
    List<User> users = this.userMapper.selectList(wrapper);  
    for (User user : users) {  
        System.out.println(user);  
    }  
}

public void testSelect(){  
    QueryWrapper<User> wrapper = new QueryWrapper<>();  
    //SELECT id,name,age FROM tb_user WHERE name = ? OR age = ?  
    wrapper.eq("name", "王五")  
            .or()  
            .eq("age", 21)  
            .select("id","name","age"); //指定查询的字段  
  
    List<User> users = this.userMapper.selectList(wrapper);  
    for (User user : users) {  
        System.out.println(user);  
    }  
}