Mybatis-Plus条件构造器的具体使用方法

@Test
public void testAllEq() {
	// 设置条件
	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);
	}
}

@Test
public void testEq() {
	QueryWrapper<User> wrapper = new QueryWrapper<>();

	// SELECT id,user_name,name,age,email AS mail FROM tb_user WHERE password = ? AND age >= ? AND name IN (?,?,?)
	wrapper.eq("password", "123456").ge("age", 20).in("name", "李四", "王五", "赵六");

	List<User> users = this.userMapper.selectList(wrapper);
	for (User user : users) {
		System.out.println(user);
	}
}

@Test
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);
	}
}

@Test
public void testOrderByAgeDesc() {
	QueryWrapper<User> wrapper = new QueryWrapper<>();
	// 按照年龄倒序排序
	// SELECT id,user_name,name,age,email AS mail FROM tb_user ORDER BY age DESC
	wrapper.orderByDesc("age");

	List<User> users = this.userMapper.selectList(wrapper);
	for (User user : users) {
		System.out.println(user);
	}
}

@Test
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);
	}
}

@Test
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);
	}
}