mybatis-plus查詢指定字段

mybatis-plus

select查詢語句默認是查全部字段，有兩種方法可以指定要查詢的字段

CREATE TABLE `user` ( `id` bigint(20) NOT NULL COMMENT '主鍵', `name` varchar(30) DEFAULT NULL COMMENT '姓名', `age` int(11) DEFAULT NULL COMMENT '年齡', `email` varchar(50) DEFAULT NULL COMMENT '郵箱', `manager_id` bigint(20) DEFAULT NULL COMMENT '直屬上級id', `create_time` datetime DEFAULT NULL COMMENT '創建時間', PRIMARY KEY (`id`), KEY `manager_fk` (`manager_id`), CONSTRAINT `manager_fk` FOREIGN KEY (`manager_id`) REFERENCES `user` (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8; 

user表只需要查詢出name和age兩個字段的數據，可以使用queryWrapper的select()方法指定要查詢的字段

    @Test public void selectByWrapper10() { QueryWrapper<User> queryWrapper = new QueryWrapper<>(); queryWrapper.select("name", "age").like("name", "雨"); List<User> users = userMapper.selectList(queryWrapper); users.forEach(System.out::println); } 

日志輸出sql：

DEBUG==> Preparing: SELECT name,age FROM user WHERE name LIKE ?
DEBUG==> Parameters: %雨%(String)
TRACE<== Columns: name, age
TRACE<== Row: 張雨琪, 31
TRACE<== Row: 劉紅雨, 31
DEBUG<== Total: 2

2、user表要查詢出除manager_id和create_time外其它所有字段的數據，同樣也是使用queryWrapper的select()方法

    @Test public void selectByWrapper11() { QueryWrapper<User> queryWrapper = new QueryWrapper<>(); queryWrapper.select(User.class, info -> !info.getColumn().equals("manager_id") && !info.getColumn().equals("create_time")); List<User> users = userMapper.selectList(queryWrapper); users.forEach(System.out::println); } 

日志輸出sql：

DEBUG==> Preparing: SELECT id,name,age,email FROM user
DEBUG==> Parameters:
TRACE<== Columns: id, name, age, email
TRACE<== Row: 1087982257332887553, 大boss, 40, [e-mail]
TRACE<== Row: 1088248166370832385, 王天風, 25, [e-mail]
TRACE<== Row: 1088250446457389058, 李藝偉, 28, [e-mail]
TRACE<== Row: 1094590409767661570, 張雨琪, 31, [e-mail]
TRACE<== Row: 1094592041087729666, 劉紅雨, 31, [e-mail]
DEBUG<== Total: 5