mybatisplus 条件构造器的使用

参考: https://www.jianshu.com/p/ceb1df475021 文中的三、mp的通用crud:

https://www.jianshu.com/p/c5537559ae3a

https://songzixian.com/mybatisplus/1354.html

https://baomidou.com/pages/10c804/#alleq (官网)

实战:

mybatisplus 条件构造器的使用

delete_User

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    @Autowired
    TestServer testServer;
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@PostMapping("/aaa")
    public String delete_User3 (@RequestBody User user, HttpServletRequest HttpServletRequest) {
        testServer.aaa();
        testServer.bbb();
        return "完成更新操作";
    }

tbl_b2c_user

package com.dao.entity;


import com.baomidou.mybatisplus.annotation.TableName;
import lombok.Data;

@Data
@TableName(value = "tbl_b2c_user")//-------------------指定表名-------------这个不错，还可以加上库名.表名
public class tbl_b2c_user {
    private int id;
    private String name;
}

tbl_b2c_userDao

package com.dao.mapper;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.dao.entity.tbl_b2c_user;

public interface tbl_b2c_userDao extends BaseMapper<tbl_b2c_user> {
}

TestServer

package com.server.Delete_user;

import com.baomidou.dynamic.datasource.annotation.DS;
import com.dao.entity.tbl_b2c_user;
import com.dao.mapper.tbl_b2c_userDao;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.ArrayList;
import java.util.List;

@DS("staging_B2c")
@Service
public class TestServer {
    //    测试使用构造器写sql
    @Autowired
    com.dao.mapper.tbl_b2c_userDao tbl_b2c_userDao;

//    更新操作
    public void aaa(){
    com.dao.entity.tbl_b2c_user tbl_b2c_user=new tbl_b2c_user();
    tbl_b2c_user.setId(2);
    tbl_b2c_user.setName("更新test测试2");
    tbl_b2c_userDao.updateById(tbl_b2c_user);//根据id进行更新，没有传值的属性就不会更新
}
    //in查询操作
    public void bbb(){
        List<Integer> idList = new ArrayList<>();
        idList.add(1);
        idList.add(2);
        idList.add(3);
        List<tbl_b2c_user> employees = tbl_b2c_userDao.selectBatchIds(idList);
        System.out.println(employees);
        employees.forEach(System.out::println);
    }

//模糊查询
public void ccc(){
    QueryWrapper<tbl_b2c_user> queryWrapper = new QueryWrapper<>();
    //模糊查询
    queryWrapper.like("name", "我是强爷");
    List<tbl_b2c_user> users = tbl_b2c_userDao.selectList(queryWrapper);

后记: 发现园可以这么写

@Test
    public void testOptimisticLocker(){
        //查询用户的信息
        User user = userMapper.selectById(2L);
        //修改用户的信息
        user.setName("丁七岁");
        user.setEmail("qisui123456@qq.com");
        //执行更新的操作
        userMapper.updateById(user);
    }
https://blog.csdn.net/qq_43612538/article/details/105824506

public void bbb(){
    NewTable NewTable=new NewTable();     这个是实体类
    NewTable.setName("张三");
    NewTable.setAge(1);
    NewTable.setGender("小班");
    test_Dao.insert(NewTable);          
    }

如果后面忘了mybatis操作数据库那么就按下面顺序看

mybatis 有xml 怎么用

https://www.cnblogs.com/kaibindirver/p/15025758.html

https://www.cnblogs.com/kaibindirver/p/15240918.html

mybatis 注解使用

https://www.cnblogs.com/kaibindirver/p/15047034.html

mp多数据源使用

https://www.cnblogs.com/kaibindirver/p/15121436.html

记录一些常用的

线上项目，凡哥写的

可以用映射的方法获取要比对的字段如下面的 OrderEntity::getUserId 意思是拿OrderEntity 里面的userId字段

.eq(OrderEntity::getUserId, req.getUserId())

allEq 全部

例1: allEq({id:1,name:"老王",age:null})--->id = 1 and name = '老王' and age is null
例2: allEq({id:1,name:"老王",age:null}, false)--->id = 1 and name = '老王' #加false 就是查询的值为空的就过滤掉这个查询条件
例3: allEq(true,{id:1,name:"老王",age:null}) true --->id = 1 and name = '老王' and age is null false -->不需要查询条件--------这里可以结合 13、判断返回变量是否为空简写返回为true or false 这个方法来用，场景是是否需要条件搜索 https://www.cnblogs.com/kaibindirver/p/11761456.html

这里面要放进一个字典有2种方法

一种创建 map

Map m1 = new HashMap();
m1.put("user_id", "1420");

一种字符转 map

import com.alibaba.fastjson.JSONObject;

String m="{\"user_id\":\"1420\"}";

JSONObject m1= JSONObject.parseObject(m);

eq 等于

eq("name", "老王")--->name = '老王'

ne 不等于 <>

`ne("name", "老王")`--->`name <> '老王'`

gt 大于 >

`gt("age", 18)`--->`age > 18`

ge 大于等于 >=

`ge("age", 18)`--->`age >= 18`

lt 小于 <

lt("age", 18)--->age < 18

le 小于等于 <==

`le("age", 18)`--->`age <= 18`

between

`between("age", 18, 30)`--->`age between 18 and 30`

notBetween

`notBetween("age", 18, 30)`--->`age not between 18 and 30`

like

like("name", "王")--->name like '%王%'

notLike

notLike("name", "王")--->name not like '%王%'

likeLeft

likeLeft("name", "王")--->name like '%王'

likeRight

likeRight("name", "王")--->name like '王%'

isNull

isNull("name")--->name is null

isNotNull

isNotNull("name")--->name is not null

in

in("age",{1,2,3})--->age in (1,2,3)

notIn

notIn("age", 1, 2, 3)--->age not in (1,2,3)

inSql

inSql("age", "1,2,3,4,5,6")--->age in (1,2,3,4,5,6)

--->id in (select id from table where id < 3)

notInSql

notInSql("age", "1,2,3,4,5,6")--->age not in (1,2,3,4,5,6)

notInSql("id", "select id from table where id < 3")--->id not in (select id from table where id < 3)

groupBy

groupBy("id", "name")--->group by id,name

orderByAsc

orderByAsc("id", "name")--->order by id ASC,name ASC

orderByDesc

orderByDesc("id", "name")--->order by id DESC,name DESC

orderBy

orderBy(true, true, "id", "name")--->order by id ASC,name ASC

having

having("sum(age) > 10")--->having sum(age) > 10

having("sum(age) > {0}", 11)--->having sum(age) > 11

or

eq("id",1).or().eq("name","老王")--->id = 1 or name = '老王'

OR嵌套

or(i -> i.eq("name", "李白").ne("status", "活着"))--->or (name = '李白' and status <> '活着')

and

and(i -> i.eq("name", "李白").ne("status", "活着"))--->and (name = '李白' and status <> '活着')

nested

nested(i -> i.eq("name", "李白").ne("status", "活着"))--->(name = '李白' and status <> '活着')

apply 拼接 sql 该方法可用于数据库函数

apply("id = 1")--->id = 1

apply("date_format(dateColumn,'%Y-%m-%d') = {0}", "2008-08-08")--->date_format(dateColumn,'%Y-%m-%d') = '2008-08-08'")

只能调用一次,多次调用以最后一次为准有sql注入的风险,请谨慎使用

last("limit 1")

exists ---这个就是判断是否执行前面sql语句的 ---select * from tbl_b2c_user where id=5 and exists(select user_id from tbl_b2c_user where id=1)

exists("select id from table where age = 1")--->exists (select id from table where age = 1)

notExists

和exists相反