文章目录
SpringBoot 整合 MybatisPlus 增删改查
一、注解的简单使用
// 指定表明
@TableName("user")
public class User {
// 指定主键
@TableId
private String id;
// 指定数据库字段
@TableField("username")
private String username;
private String password;
// 该字段数据库中不存在
@TableField(exist = false)
private String remark;
private Integer age;
}
二、获取 UserMapper 对象
@Autowired(required = false)
private UserMapper userMapper;
required = false
不加这个条件时会报错
三、插入数据
// 插入
User user = new User();
user.setId("4");
user.setUsername("4");
// 当某个字段为null时，该字段不会插入
// INSERT INTO user ( id, username ) VALUES ( ?, ? )
user.setPassword("3");
int result = userMapper.insert(user);
System.out.println(result);
四、查询数据
1.普通查询
- 查询全部
// 查询全部
List<User> list = userMapper.selectList(null);
Assert.assertEquals(2,list.size());
for(User user : list){
System.out.println(user);
}
- 根据 id 查询
// 查询单个
User user = userMapper.selectById("2");
System.out.println(user);
- 根据 idList 查询多个
// 查询多个
List<String> idList = Arrays.asList("1","2","3");
List<User> list = userMapper.selectBatchIds(idList);
for(User user : list){
System.out.println(user);
}
- 多个 where 条件查询
// 多个where条件查询
Map<String,Object> map = new HashMap<>();
// k：数据库中字段名
map.put("id","2");
map.put("username","2");
// SELECT id,username,password FROM user WHERE id = ? AND username = ?
List<User> list = userMapper.selectByMap(map);
for(User user : list){
System.out.println(user);
}
2.条件构造器查询
- 查询姓名中含有‘文’，年龄小于60的
// 查询姓名中含有‘文’，年龄小于60的
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
// QueryWrapper<User> queryWrapper = Wrappers.<User>query();
queryWrapper.like("username","文").lt("age",60);
List<User> list = userMapper.selectList(queryWrapper);
list.forEach(System.out::print);
- 查询姓名中含有‘文’，年龄小于60大于40的，password不为空
// 查询姓名中含有‘文’，年龄小于60大于40的，password不为空
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.like("username","文").between("age",40,60).isNotNull("password");
List<User> list = userMapper.selectList(queryWrapper);
list.forEach(System.out::print);
- name like ‘王%’ or age>=25 order by age desc,id asc
// name like '王%' or age>=25 order by age desc,id asc
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.likeRight("name","王").or().ge("age",25)
.orderByDesc("age").orderByAsc("id");
List<User> list = userMapper.selectList(queryWrapper);
list.forEach(System.out::print);
- data_format(create_time,’%Y-%m-%d’) and manager_id in (select id from user where name like ‘王%’)
// data_format(create_time,'%Y-%m-%d') and manager_id in (select id from user where name like '王%')
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.apply("data_format(create_time,'%Y-%m-%d')={0}","2019-02-04")
.inSql("manager_id","select id from user where username like '王%'");
// WHERE (data_format(create_time,'%Y-%m-%d')=? AND
// manager_id IN (select id from user where username like '王%'))
List<User> list = userMapper.selectList(queryWrapper);
list.forEach(System.out::print);
- name like ‘王%’ and (age<40 or email is not null)
// name like '王%' and (age<40 or email is not null)
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.likeRight("name","王")
.and(wq->wq.lt("age",40).or().isNotNull("email"));
// WHERE (name LIKE ? AND (age < ? OR email IS NOT NULL))
List<User> list = userMapper.selectList(queryWrapper);
list.forEach(System.out::print);
- name like ‘王%’ or (age < 40 and age >20 and email is not null)
// name like '王%' or (age < 40 and age >20 and email is not null)
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.likeRight("name","王")
.or(wq->wq.lt("age",40).gt("age",20).isNotNull("email"));
// WHERE (name LIKE ? OR (age < ? AND age > ? AND email IS NOT NULL))
List<User> list = userMapper.selectList(queryWrapper);
list.forEach(System.out::print);
- (age < 40 or email is not null) name like ‘王%’
// (age < 40 or email is not null) name like '王%'
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.nested(wq->wq.lt("age",40).or().isNotNull("email"))
.likeRight("name","王");
// WHERE ((age < ? OR email IS NOT NULL) AND name LIKE ?)
List<User> list = userMapper.selectList(queryWrapper);
list.forEach(System.out::print);
- age in (13,14,15,16) limit 1
// age in (13,14,15,16) limit 1
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.in("age",Arrays.asList(13,14,15,16)).last("limit 1");
// WHERE (age IN (?,?,?,?)) limit 1
List<User> list = userMapper.selectList(queryWrapper);
list.forEach(System.out::print);
- 查询指定字段
// select id
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.select("id");
List<User> list = userMapper.selectList(queryWrapper);
list.forEach(System.out::print);
- 字段为空时，不加入查询
String name = "aowei";
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.like(name.equals(null),"name",name);
List<User> list = userMapper.selectList(queryWrapper);
list.forEach(System.out::print);
- 实体作为条件构造器构造方法的参数
User user = new User();
user.setId("2");
user.setUsername("2");
QueryWrapper<User> queryWrapper = new QueryWrapper<>(user);
// WHERE id=? AND username=?
List<User> list = userMapper.selectList(queryWrapper);
list.forEach(System.out::print);
- Map 类型参数
Map<String,Object> map = new HashMap<>();
map.put("id","2");
map.put("username","2");
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.allEq(map);
// WHERE (id = ? AND username = ?)
List<User> list = userMapper.selectList(queryWrapper);
list.forEach(System.out::print);
- 返回 Map 类型结果集
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.select("id","username");
List<Map<String,Object>> list = userMapper.selectMaps(queryWrapper);
list.forEach(System.out::print);
- 查询总记录数
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.select("id");
int result = userMapper.selectCount(queryWrapper);
System.out.println(result);
3.Lambda 条件构造器查询
- 仿误写
// LambdaQueryWrapper<User> lambda = new QueryWrapper<User>().lambda();
// LambdaQueryWrapper<User> lambda = new LambdaQueryWrapper<>();
LambdaQueryWrapper<User> lambda = Wrappers.<User>lambdaQuery();
lambda.like(User::getUsername,"文");
List<User> list = userMapper.selectList(lambda);
list.forEach(System.out::print);
4.分页查询
- 新建配置类
//Spring boot方式
@EnableTransactionManagement
@Configuration
@MapperScan("com.baomidou.cloud.service.*.mapper*")
public class MybatisPlusConfig {
@Bean
public PaginationInterceptor paginationInterceptor() {
PaginationInterceptor paginationInterceptor = new PaginationInterceptor();
// 设置请求的页面大于最大页后操作， true调回到首页，false 继续请求 默认false
// paginationInterceptor.setOverflow(false);
// 设置最大单页限制数量，默认 500 条，-1 不受限制
// paginationInterceptor.setLimit(500);
// 开启 count 的 join 优化,只针对部分 left join
paginationInterceptor.setCountSqlParser(new JsqlParserCountOptimize(true));
return paginationInterceptor;
}
}
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
Page<User> page = new Page<>(1,2);
IPage<User> iPage = userMapper.selectPage(page,queryWrapper);
System.out.println("总页数："+iPage.getPages());
System.out.println("总记录："+iPage.getTotal());
List<User> list = iPage.getRecords();
list.forEach(System.out::println);
五、更新数据
1.普通更新
- 根据 id 更新
User user = new User();
user.setId("2");
user.setUsername("22222");
int result = userMapper.updateById(user);
System.out.println(result);
2.条件构造器更新
UpdateWrapper<User> updateWrapper = new UpdateWrapper<>();
updateWrapper.eq("id","2");
User user = new User();
user.setAge(22);
int result = userMapper.update(user,updateWrapper);
System.out.println(result);
UpdateWrapper<User> updateWrapper = new UpdateWrapper<>();
updateWrapper.eq("id","2").set("age",23);
int result = userMapper.update(null,updateWrapper);
System.out.println(result);
3.Lambda 条件构造器更新
LambdaUpdateWrapper<User> lambdaUpdate = Wrappers.<User>lambdaUpdate();
lambdaUpdate.eq(User::getId,"2").set(User::getAge,23);
int result = userMapper.update(null,lambdaUpdate);
System.out.println(result);
六、删除数据
- 删除数据时，同样有条件构造器删除
- 使用的是 QueryWrapper
int result = userMapper.deleteById("2");
Map<String,Object> map = new HashMap<>();
// k：数据库中字段名
map.put("id","2");
map.put("username","2");
int result = userMapper.deleteByMap(map);
int result = userMapper.deleteBatchIds(Arrays.asList("1","2","3"));
