MyBatisPlus条件构造器的实现示例
作者：黄晶谛
本文主要介绍了MyBatisPlus条件构造器的实现示例,主要包括了QueryWrapper,UpdateWrapper,LambdaQueryWrapper,LambdaUpdateWrapper这四种,具有一定的参考价值,感兴趣的可以了解下
主要包括以下几种：
- QueryWrapper
- UpdateWrapper
- LambdaQueryWrapper
- LambdaUpdateWrapper
用法示例如下：
QueryWrapper
1 查询示例
/**
* ==> Preparing: SELECT id,user_name AS name,age,email,is_deleted FROM user WHERE is_deleted=0 AND (user_name LIKE ? AND age BETWEEN ? AND ? AND email IS NOT NULL)
* ==> Parameters: %雷%(String), 10(Integer), 30(Integer)
* <== Columns: id, name, age, email, is_deleted
* <== Row: 1734579107187970050, 李雷, 12, lilei@giser.com, 0
* <== Total: 1
* 用户列表信息为：[User(id=1734579107187970050, name=李雷, age=12, email=lilei@giser.com, isDeleted=0)]
*/
@Test
void testQueryWrapper01(){
// 查询用户名包含“雷”字，且年龄在20到30之间，邮箱不为null的用户信息
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.like("user_name", "雷")
.between("age", 10, 30)
.isNotNull("email");
List<User> userList = userMapper.selectList(queryWrapper);
log.info("用户列表信息为：{}", userList);
}
/**
* SELECT id,user_name AS name,age,email,is_deleted FROM user WHERE is_deleted=0 ORDER BY age DESC,id ASC
*/
@Test
void testOrderBy02(){
// 查询用户列表，按照年龄降序，按照ID升序排序
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.orderByDesc("age")
.orderByAsc("id");
List<User> userList = userMapper.selectList(queryWrapper);
log.info("用户列表信息为：{}", userList);
}
- 组装select子句
/**
* 组装select子句
*/
@Test
void testCompSubSql(){
// 只查询部分字段
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.select("user_name", "age", "email");
List<Map<String, Object>> maps = userMapper.selectMaps(queryWrapper);
log.info("查询部分字段：{}", maps);
}
- 子查询
/**
* 子查询
* ==> Preparing: SELECT id,user_name AS name,age,email,is_deleted FROM user WHERE is_deleted=0 AND (id IN (select id from t_user where age > 10))
* ==> Parameters:
* <== Columns: id, name, age, email, is_deleted
* <== Row: 1, Jone, 18, test1@baomidou.com, 0
* <== Row: 2, 窃听风云, 23, giserDev@163.com, 0
* <== Row: 3, Tom, 28, test3@baomidou.com, 0
* <== Total: 3
* 查询结果为：[User(id=1, name=Jone, age=18, email=test1@baomidou.com, isDeleted=0), User(id=2, name=窃听风云, age=23, email=giserDev@163.com, isDeleted=0), User(id=3, name=Tom, age=28, email=test3@baomidou.com, isDeleted=0)]
*/
@Test
void testCompSubSql2(){
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.inSql("id", "select id from t_user where age > 10");
List<User> userList = userMapper.selectList(queryWrapper);
log.info("查询结果为：{}", userList);
}
2 删除示例
/**
* ==> Preparing: UPDATE user SET is_deleted=1 WHERE is_deleted=0 AND (user_name = ? AND age = ?)
* ==> Parameters: 李雷(String), 12(Integer)
* <== Updates: 1
*/
@Test
void testDelete03(){
// 删除功能测试，此时为逻辑删除，实际上执行的是更新语句
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.eq("user_name", "李雷")
.eq("age", 12);
int delete = userMapper.delete(queryWrapper);
log.info("用户列表信息为：{}", delete);
}
3 更新示例
/**
* ==> Preparing: UPDATE user SET user_name=?, age=?, email=? WHERE is_deleted=0 AND (user_name = ? AND age = ? OR email IS NULL)
* ==> Parameters: 韩梅梅(String), 23(Integer), giserDev@163.com(String), 李雷(String), 12(Integer)
* <== Updates: 1
*/
@Test
void testUpdate01(){
// 更新姓名为”李雷“且年龄为12岁，或邮箱为空的数据
// case 1: 使用QueryWrapper
// 设定更新条件
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.eq("user_name", "李雷")
.eq("age", 12)
.or()
.isNull("email");
// 设定更新数据
User updUser = new User();
updUser.setEmail("giserDev@163.com");
updUser.setName("韩梅梅");
updUser.setAge(23);
int update = userMapper.update(updUser, queryWrapper);
log.info("更新条数为：{}", update);
}
- MybatisPlus条件优先级：lambda表达式内的逻辑优先运算
/**
* ==> Preparing: UPDATE user SET user_name=?, age=?, email=? WHERE is_deleted=0 AND (user_name LIKE ? AND (age > ? OR email IS NULL))
* ==> Parameters: 窃听风云(String), 23(Integer), giserDev@163.com(String), %J%(String), 18(Integer)
* <== Updates: 1
*/
@Test
void testUpdate02(){
// 将用户名中包含有J并且（年龄大于18或邮箱为null）的用户信息修改
// case 2: lambda表达式内的逻辑优先运算
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.like("user_name", "J")
.and(
wrapper -> wrapper.gt("age", 18)
.or()
.isNull("email")
);
// 设定更新数据
User updUser = new User();
updUser.setEmail("giserDev@163.com");
updUser.setName("窃听风云");
updUser.setAge(23);
int update = userMapper.update(updUser, queryWrapper);
log.info("更新条数为：{}", update);
}
}
UpdateWrapper
/**
* UPDATE user SET user_name=?,email=? WHERE is_deleted=0 AND (user_name = ? AND (age > ? AND email IS NULL))
*/
@Test
void testUpdateWrapper(){
UpdateWrapper<User> updateWrapper = new UpdateWrapper<>();
updateWrapper.eq("user_name", "kitty")
.and(wrapper -> wrapper.gt("age", 10).isNull("email"));
updateWrapper.set("user_name", "gis2023").set("email", "gis2023@163.com");
int update = userMapper.update(updateWrapper);
log.info("更新条数为：{}", update);
// int update1 = userMapper.update(null, updateWrapper);
// log.info("更新条数为：{}", update1);
}
4 条件组装
示例一
/**
* ==> Preparing: SELECT id,user_name AS name,age,email,is_deleted FROM user WHERE is_deleted=0 AND (user_name LIKE ? AND age >= ? AND age <= ?)
* ==> Parameters: %张三%(String), 10(Integer), 20(Integer)
* <== Total: 0
*/
@Test
void testDynamicSqlWrapper(){
String username = "张三";
Integer ageBgn = 10;
Integer ageEnd = 20;
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
if (StringUtils.isNotBlank(username)){
queryWrapper.like("user_name", username);
}
if (ageBgn != null){
queryWrapper.ge("age", ageBgn);
}
if (ageEnd != null){
queryWrapper.le("age", ageEnd);
}
List<User> userList = userMapper.selectList(queryWrapper);
log.info("查询记录为：{}", userList);
}
示例二 使用condition
/**
* 使用condition组装条件
* ==> Preparing: SELECT id,user_name AS name,age,email,is_deleted FROM user WHERE is_deleted=0 AND (user_name LIKE ? AND age >= ? AND age <= ?)
* ==> Parameters: %张三%(String), 10(Integer), 20(Integer)
* <== Total: 0
*/
@Test
void testDynamicSqlWrapper02(){
String username = "张三";
Integer ageBgn = 10;
Integer ageEnd = 20;
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.like(StringUtils.isNotBlank(username), "user_name", username)
.ge(ageBgn != null, "age", ageBgn)
.le(ageEnd != null, "age", ageEnd);
List<User> userList = userMapper.selectList(queryWrapper);
log.info("查询记录为：{}", userList);
}
LambdaQueryWrapper
/**
*
* ==> Preparing: SELECT id,user_name AS name,age,email,is_deleted FROM user WHERE is_deleted=0 AND (user_name LIKE ? AND age >= ? AND age <= ?)
* ==> Parameters: %张三%(String), 10(Integer), 20(Integer)
* <== Total: 0
*/
@Test
void testDynamicSqlWrapper03(){
String username = "张三";
Integer ageBgn = 10;
Integer ageEnd = 20;
LambdaQueryWrapper<User> lambdaQueryWrapper = new LambdaQueryWrapper<>();
lambdaQueryWrapper.like(StringUtils.isNotBlank(username), User::getName, username)
.ge(ageBgn != null, User::getAge, ageBgn)
.le(ageEnd != null, User::getAge, ageEnd);
List<User> userList = userMapper.selectList(lambdaQueryWrapper);
log.info("查询记录为：{}", userList);
}
LambdaUpdateWrapper
/**
* ==> Preparing: UPDATE user SET user_name=?,email=? WHERE is_deleted=0 AND (user_name = ? AND (age > ? AND email IS NULL))
* ==> Parameters: gis2023(String), gis2023@163.com(String), kitty(String), 10(Integer)
* <== Updates: 0
*/
@Test
void testUpdateWrapper02(){
LambdaUpdateWrapper<User> lambdaUpdateWrapper = new LambdaUpdateWrapper<>();
lambdaUpdateWrapper.eq(User::getName, "kitty")
.and(wrapper -> wrapper.gt(User::getAge, 10).isNull(User::getEmail));
lambdaUpdateWrapper.set(User::getName, "gis2023").set(User::getEmail, "gis2023@163.com");
int update = userMapper.update(lambdaUpdateWrapper);
log.info("更新条数为：{}", update);
// int update1 = userMapper.update(null, lambdaUpdateWrapper);
// log.info("更新条数为：{}", update1);
}
常用
最常用的是LambdaQueryWrapper 和 LambdaUpdateWrapper
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