一 、MyBatisPlus 介绍 转自mybatisplus官网 下方附有mybatisplus官方网站
MyBatis-Plus(简称 MP)是一个 MyBatis 的增强工具,在 MyBatis 的基础上只做增强不做改变,为简化开发、提高效率而生。
(1)愿景
我们的愿景是成为 MyBatis 最好的搭档,就像 魂斗罗 中的 1P、2P,基友搭配,效率翻倍。
(2)特性
①无侵入:只做增强不做改变,引入它不会对现工程产生影响,如丝般顺滑
②损耗小:启动即会自动注入基本 CURD,性能基本无损耗,直接面向对象操作
③强大的 CRUD 操作:内置通用 Mapper、通用 Service,仅仅通过少量配置即可实现单表大部分 CRUD 操作,更有强大的条件构造器,满足各类使用需求
④支持 Lambda 形式调用:通过 Lambda 表达式,方便的编写各类查询条件,无需再担心字段写错
⑤支持主键自动生成:支持多达 4 种主键策略(内含分布式唯一 ID 生成器 - Sequence),可自由配置,完美解决主键问题
⑥支持 ActiveRecord 模式:支持 ActiveRecord 形式调用,实体类只需继承 Model 类即可进行强大的 CRUD 操作
⑦支持自定义全局通用操作:支持全局通用方法注入( Write once, use anywhere )
⑧内置代码生成器:采用代码或者 Maven 插件可快速生成 Mapper 、 Model 、 Service 、 Controller 层代码,支持模板引擎,更有超多自定义配置等您来使用
⑨内置分页插件:基于 MyBatis 物理分页,开发者无需关心具体操作,配置好插件之后,写分页等同于普通 List 查询
⑩分页插件支持多种数据库:支持 MySQL、MariaDB、Oracle、DB2、H2、HSQL、SQLite、Postgre、SQLServer2005、SQLServer 等多种数据库
⑪内置性能分析插件:可输出 Sql 语句以及其执行时间,建议开发测试时启用该功能,能快速揪出慢查询
⑫内置全局拦截插件:提供全表 delete 、 update 操作智能分析阻断,也可自定义拦截规则,预防误操作
代码及文档发布地址
官方地址:
http://mp.baomidou.com
代码发布地址:
Github: https://github.com/baomidou/mybatis-plus
Gitee: https://gitee.com/baomidou/mybatis-plus
文档发布地址:
http://mp.baomidou.com/#/?id=%E7%AE%80%E4%BB%8B
二、 springboot 快速开始使用
快速开始参考:http://mp.baomidou.com/guide/quick-start.html
测试项目: mybatis_plus
数据库:mybatis_plus
1 创建并初始化数据库
(1)创建数据库:
mybatis_plus
(2)创建 User 表
其表结构如下:
其对应的数据库 Schema 脚本如下:
DROP TABLE IF EXISTS user;
CREATE TABLE user
(
id BIGINT(20) NOT NULL COMMENT '主键ID',
name VARCHAR(30) NULL DEFAULT NULL COMMENT '姓名',
age INT(11) NULL DEFAULT NULL COMMENT '年龄',
email VARCHAR(50) NULL DEFAULT NULL COMMENT '邮箱',
PRIMARY KEY (id)
);
其对应的数据库 Data 脚本如下:
DELETE FROM user;
INSERT INTO user (id, name, age, email) VALUES
(1, 'Jone', 18, 'test1@baomidou.com'),
(2, 'Jack', 20, 'test2@baomidou.com'),
(3, 'Tom', 28, 'test3@baomidou.com'),
(4, 'Sandy', 21, 'test4@baomidou.com'),
(5, 'Billie', 24, 'test5@baomidou.com');
2 初始化工程
使用 Spring Initializr 快速初始化一个 Spring Boot 工程
Group:com.Daniel
Artifact:mybatis-plus
版本:2.0.7.RELEASE
<mybatis-plus.version>3.0.5</mybatis-plus.version>
pom.xml
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>daniel-parent</artifactId>
<groupId>com.daniel</groupId>
<version>0.0.1-SNAPSHOT</version>
<relativePath>../daniel-parent/pom.xml</relativePath>
</parent>
<modelVersion>4.0.0</modelVersion>
<groupId>com.daniel</groupId>
<artifactId>mybatis-plus</artifactId>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<!--mybatis-plus-->
<dependency>
<groupId>com.baomidou</groupId>
<artifactId>mybatis-plus-boot-starter</artifactId>
<version>3.0.5</version>
</dependency>
<!--mysql-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
</dependency>
<!--lombok用来简化实体类-->
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
</dependency>
</dependencies>
</project>
3 配置
在 application.properties 配置文件中添加 MySQL 数据库的相关配置:
注意:
(1)springboot2.0.x和springboot2.1.x使用不同
springboot2.1.x版本时候,写数据库驱动和数据库路径时候不一样的
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/mybatis_plus?serverTimezone=GMT%2B8
(2)springboot1.x和springboot2.x区别
①springboot1.x底层使用spring4.x
②springboot2.x底层使用spring5.x
本工程由于父工程为2.0.7故配置文件为:(为完整配置已经进行过完整的mybatis的基本功能测试)
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/mybatis_plus
spring.datasource.username=******
spring.datasource.password=******
#mybatis日志
mybatis-plus.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImpl
#全局设置主键生成策略
#global-config 全局配置对所的类起作用
#mybatis-plus.global-config.db-config.id-type=auto
#其它主键策略:分析 IdType 源码可知
#配置的是逻辑删除的删除的两个状态值,默认也是这两个配不配都可以
mybatis-plus.global-config.db-config.logic-delete-value=1
mybatis-plus.global-config.db-config.logic-not-delete-value=0
#环境设置:dev、test、prod 本工程为SQL 执行性能分析插件时设置
spring.profiles.active=dev
4 编写代码
(1)主类
在 Spring Boot 启动类中添加 @MapperScan 注解,扫描 Mapper 文件夹
注意:扫描的包名根据实际情况修改
@SpringBootApplication
@MapperScan("com.atguigu.mybatisplus.mapper")
public class MybatisPlusApplication {
public static void main(String[] args) {
SpringApplication.run(MybatisPlusApplication.class,args);
}
}
(2)实体
创建包 entity 编写实体类 User.java(此处使用了 Lombok 简化代码)
@Data
public class User {
private Long id;
private String name;
private Integer age;
private String email;
}
Lombok使用参考:
https://blog.csdn.net/motui/article/details/79012846
(3)mapper
创建包 mapper 编写Mapper 接口: UserMapper.java
@Component
public interface UserMapper extends BaseMapper<User> {
}
5 开始使用
添加测试类,进行功能测试:
@RunWith(SpringRunner.class)
@SpringBootTest
public class MybatisPlusApplicationTests {
@Autowired
private UserMapper userMapper;
@Test
public void testSelectList() {
System.out.println(("----- selectAll method test ------"));
//UserMapper 中的 selectList() 方法的参数为 MP 内置的条件封装器 Wrapper
//所以不填写就是无任何条件
List<User> users = userMapper.selectList(null);
users.forEach(System.out::println);
}
}
6 基本的crud
以下为测试代码
package com.daniel.mp;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
/**
* @author Daniel
* @Description:
*/
@SpringBootApplication
public class MpApplication {
public static void main(String[] args) {
SpringApplication.run(MpApplication.class,args);
}
}
package com.daniel.mp.entity;
import com.baomidou.mybatisplus.annotation.*;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.ToString;
import java.util.Date;
import java.util.logging.FileHandler;
/**
* @author Daniel
* @Description:
*/
@Data
@ToString
@NoArgsConstructor
@AllArgsConstructor
public class User {
@TableId(type = IdType.ID_WORKER)
private Long id;
private String name;
private Integer age;
private String email;
@TableField(fill = FieldFill.INSERT)
private Date createTime;
@TableField(fill = FieldFill.INSERT_UPDATE)
private Date updateTime;
@Version
@TableField(fill = FieldFill.INSERT)
private Integer version;
@TableLogic
@TableField(fill = FieldFill.INSERT)
private Integer deleted;
}
package com.daniel.mp.mapper;
import com.atguigu.mp.entity.User;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import org.springframework.stereotype.Component;
/**
* @author Daniel
* @Description:
*/
@Component
public interface UserMapper extends BaseMapper<User> {
}
package com.daniel.mp.config;
import com.baomidou.mybatisplus.core.injector.ISqlInjector;
import com.baomidou.mybatisplus.extension.injector.LogicSqlInjector;
import com.baomidou.mybatisplus.extension.plugins.OptimisticLockerInterceptor;
import com.baomidou.mybatisplus.extension.plugins.PerformanceInterceptor;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringBootConfiguration;
import org.springframework.context.annotation.Bean;
import org.springframework.transaction.annotation.EnableTransactionManagement;
/**
* @author Daniel
* @Description:
*/
@MapperScan("com.atguigu.mp.mapper")
@SpringBootConfiguration
@EnableTransactionManagement
public class MybatisPlusConfig {
/**
* 乐观锁插件
*/
@Bean
public OptimisticLockerInterceptor optimisticLockerInterceptor(){
return new OptimisticLockerInterceptor();
}
/**
* 逻辑删除插件
*/
@Bean
public ISqlInjector sqlInjector(){
return new LogicSqlInjector();
}
/**
* SQL 执行性能分析插件
* 开发环境使用,线上不推荐。 maxTime 指的是 sql 最大执行时长
*/
@Profile({"dev","test"})// 设置 dev test 环境开启
@Bean
public PerformanceInterceptor performanceInterceptor(){
PerformanceInterceptor performanceInterceptor = new PerformanceInterceptor();
performanceInterceptor.setMaxTime(100);//ms,超过此处设置的ms则sql不执行
performanceInterceptor.setFormat(true);
return performanceInterceptor;
}
}
package com.daniel.mp.handler;
import com.baomidou.mybatisplus.core.handlers.MetaObjectHandler;
import org.apache.ibatis.reflection.MetaObject;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;
import java.util.Date;
/**
* @author Daniel
* @Description:
*/
@Component
public class MyMetaObjectHandler implements MetaObjectHandler {
private static final Logger LOGGER = LoggerFactory.getLogger(MetaObjectHandler.class);
@Override
public void insertFill(MetaObject metaObject) {
LOGGER.debug("开始insert fill ...");
this.setFieldValByName("createTime",new Date(),metaObject);
this.setFieldValByName("updateTime",new Date(),metaObject);
this.setFieldValByName("version",1,metaObject);
this.setFieldValByName("deleted",0,metaObject);
}
@Override
public void updateFill(MetaObject metaObject) {
LOGGER.debug("开始update fill ...");
this.setFieldValByName("updateTime",new Date(),metaObject);
}
}
package com.daniel.mp.test;
import com.daniel.mp.entity.User;
import com.daniel.mp.mapper.UserMapper;
import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.core.toolkit.IdWorker;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* @author Daniel
* @Description:
*/
//public final class SpringRunner extends org.springframework.test.context.junit4.SpringJUnit4ClassRunner {
@RunWith(SpringRunner.class)
@SpringBootTest
public class MybatisPlusApplicationTests {
@Autowired
UserMapper userMapper;
@Test
public void testSelect() {
// List<User> users = userMapper.selectList(null);
// users.forEach(System.out::println);
/*
* User(id=1, name=Jone, age=18, email=test1@baomidou.com)
*User(id=2, name=Jack, age=20, email=test2@baomidou.com)
*User(id=3, name=Tom, age=28, email=test3@baomidou.com)
*User(id=4, name=Sandy, age=21, email=test4@baomidou.com)
*User(id=5, name=Billie, age=24, email=test5@baomidou.com)
* */
//SELECT id,name,age,email FROM user WHERE id=?
// User user = userMapper.selectById(1L);
// System.err.println(user);//User(id=1, name=Jone, age=18, email=test1@baomidou.com)
//
// List<Long> ids = Arrays.asList(1L, 2L, 3L);
// //SELECT id,name,age,email,create_time,update_time,version FROM user WHERE id IN ( ? , ? , ? )
// List<User> users = userMapper.selectBatchIds(ids);
// users.forEach(System.err::println);
//当配置了性能优化时,设置为1ms时
// The SQL execution time is too large, please optimize !
/*
User(id=1, name=Jone, age=18, email=test1@baomidou.com)
User(id=2, name=Jack, age=20, email=test2@baomidou.com)
User(id=3, name=Tom, age=28, email=test3@baomidou.com)
*/
// Map<String,Object> map = new HashMap<>();
// map.put("name","Jack");
// map.put("age",20);
// List<User> users = userMapper.selectByMap(map);
// users.forEach(System.err::println);//User(id=2, name=Jack, age=20, email=test2@baomidou.com)
//本查询需要借助于分页插件 PaginationInterceptor 与 SSM框架整合不同
Page<User> page = new Page<>(1,2);
IPage<User> userIPage = userMapper.selectPage(page, null);
List<User> users = userIPage.getRecords();
users.forEach(System.err::println);
System.err.println("当前页:"+page.getCurrent());
System.err.println("每页显示记录数:"+page.getSize());
System.err.println("总记录数:"+page.getTotal());
System.err.println("总页数:"+page.getPages());
System.err.println("总记录数:"+page.getTotal());
System.err.println("是否下一页:"+page.hasNext());
System.err.println("是否上一页:"+page.hasPrevious());
/*
SELECT
id,
name,
age,
email,
create_time,
update_time,
version,
deleted
FROM
user
WHERE
deleted=0 LIMIT 0,2
User(id=1, name=Jone, age=18, email=test1@baomidou.com, createTime=Thu Aug 15 09:31:29 GMT+08:00 2019, updateTime=Thu Aug 15 09:31:29 GMT+08:00 2019, version=1, deleted=0)
User(id=2, name=Jack, age=20, email=test2@baomidou.com, createTime=Thu Aug 15 09:31:29 GMT+08:00 2019, updateTime=Thu Aug 15 09:31:29 GMT+08:00 2019, version=1, deleted=0)
当前页:1
每页显示记录数:2
总记录数:6
总页数:3
总记录数:6
是否下一页:true
是否上一页:false
*/
//本查询需要借助于分页插件 PaginationInterceptor
// Page<User> page = new Page<>(1,5);
// IPage<Map<String, Object>> mapPage = userMapper.selectMapsPage(page, null);//??????
// //注意:此行必须使用 mapIPage 获取记录列表,否则会数据类型转换错误
// List<Map<String, Object>> users = mapPage.getRecords();
// users.forEach(System.err::println);
// System.err.println("当前页:"+page.getCurrent());
// System.err.println("每页显示记录数:"+page.getSize());
// System.err.println("总记录数:"+page.getTotal());
// System.err.println("总页数:"+page.getPages());
// System.err.println("总记录数:"+page.getTotal());
// System.err.println("是否下一页:"+page.hasNext());
// System.err.println("是否上一页:"+page.hasPrevious());
/*
SELECT
id,
name,
age,
email,
create_time,
update_time,
version,
deleted
FROM
user
WHERE
deleted=0 LIMIT 0,5
{update_time=2019-08-15 09:31:29.0, deleted=0, create_time=2019-08-15 09:31:29.0, name=Jone, id=1, version=1, age=18, email=test1@baomidou.com}
{update_time=2019-08-15 09:31:29.0, deleted=0, create_time=2019-08-15 09:31:29.0, name=Jack, id=2, version=1, age=20, email=test2@baomidou.com}
{update_time=2019-08-15 09:31:29.0, deleted=0, create_time=2019-08-15 09:31:29.0, name=Tom, id=3, version=1, age=28, email=test3@baomidou.com}
{update_time=2019-08-15 09:31:29.0, deleted=0, create_time=2019-08-15 09:31:29.0, name=Sandy, id=4, version=1, age=21, email=test4@baomidou.com}
{update_time=2019-08-15 09:31:29.0, deleted=0, create_time=2019-08-15 09:31:29.0, name=Billie, id=5, version=1, age=24, email=test5@baomidou.com}
当前页:1
每页显示记录数:5
总记录数:6
总页数:2
总记录数:6
是否下一页:true
是否上一页:false
*/
}
@Test
public void testInsert() {
User user = new User();
user.setName("苏洵");
user.setEmail("sx@daniel.com");
user.setAge(182);
//加了版本号后
//INSERT INTO user ( id, name, age, email, create_time, update_time, version ) VALUES ( ?, ?, ?, ?, ?, ?, ? )
//加了时间后
//INSERT INTO user ( id, name, age, email, create_time, update_time ) VALUES ( ?, ?, ?, ?, ?, ? )
//INSERT INTO user ( id, name, age, email ) VALUES ( ?, ?, ?, ? )
int insert = userMapper.insert(user);
System.out.println("影响了" + insert + "行");//影响了1行
// //id自动回填 System.out.println(user);//User(id=1161598217527648258, name=苏明玉, age=30, email=smy@daniel.com)
}
@Test
public void testIdWorker(){
long id = new com.atguigu.mp.utils.IdWorker().nextId();
System.out.println(id);//1161599849573281792
}
@Test
public void testUpdate(){
User user = new User();
user.setId(5L);
user.setName("苏明成");
user.setEmail("smy@daniel.com");
user.setAge(30);
//UPDATE user SET name=?, age=?, email=?, update_time=? WHERE id=?
// UPDATE user SET name=?, age=?, email=? WHERE id=?
int updateById = userMapper.updateById(user);
System.out.println("修改了" + updateById + "行");//修改了1行
}
/**
* 测试 乐观锁插件
*/
@Test
public void testOptimisticLocker(){
User user = userMapper.selectById(1L);
user.setName("苏辙");
user.setAge(111);
user.setEmail("sz@daniel.com");
//UPDATE user SET name=?, age=?, email=?, create_time=?, update_time=?, version=? WHERE id=? AND version=?
//版本号如果对应不上修改就不会成功
user.setVersion(user.getVersion()-1);
int updateById = userMapper.updateById(user);
System.out.println("修改了" + updateById + "行");//修改了1行
}
@Test
public void testDelete(){
//DELETE FROM user WHERE id=?
int rows = userMapper.deleteById(3L);
System.out.println(rows + "行被删除了!!!");//1行被删除了!!!
}
@Test
public void testDeleteBatchIds() {
//DELETE FROM user WHERE id IN ( ? , ? , ? )
// int result = userMapper.deleteBatchIds(Arrays.asList(8, 9, 10));//公司基本不会用删除的命令
// System.out.println(result);
}
/**
* 测试 逻辑删除
*/
@Test
public void testLogicDelete(){
//UPDATE user SET deleted=1 WHERE id=? AND deleted=0
int rows = userMapper.deleteById(3L);
System.out.println(rows + "行被删除了!!!");//1行被删除了!!!
}
/**
* wrapper 的测试由此往下 条件构造器
* 1、delete
*2、selectOne
*3、selectCount
*4、selectList
5、selectMaps
6、selectObjs
7、update
*/
@Test
public void testWrapperSelect(){
// QueryWrapper<User> queryWrapper = new QueryWrapper<>();
// queryWrapper.isNotNull("name")
// .ge("age",28)
// .le("age",110);
// List<User> users = userMapper.selectList(queryWrapper);
// users.forEach(System.err::println);
/*
Execute SQL:
SELECT
id,
name,
age,
email,
create_time,
update_time,
version,
deleted
FROM
user
WHERE
deleted=0
AND name IS NOT NULL
AND age >= 28
AND age <= 110
*/
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.eq("name","苏大强");
User user = userMapper.selectOne(queryWrapper);
System.out.println(user);
}
}
7 条件构造器
Wrapper : 条件构造抽象类,最顶端父类
|---AbstractWrapper : 用于查询条件封装,生成 sql 的 where 条件
|---QueryWrapper : Entity 对象封装操作类,不是用lambda语法
|---UpdateWrapper : Update 条件封装,用于Entity对象更新操作
|---AbstractLambdaWrapper : Lambda 语法使用 Wrapper统一处理解析 lambda 获取 column。
|---LambdaQueryWrapper :看名称也能明白就是用于Lambda语法使用的查询Wrapper
|---LambdaUpdateWrapper : Lambda 更新封装Wrapper
/**
* @author Daniel
* @create 2019--08--15--11:41
* @Description:
*/
@RunWith(SpringRunner.class)
@SpringBootTest
public class QueryWrapperTests {
@Autowired
private UserMapper userMapper;
}
注意:以下条件构造器的方法入参中的 column 均表示数据库字段
(1) ge、gt、le、lt、isNull、isNotNull
@Test
public void testDelete(){
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper
.isNull("name")
.ge("age", 12)
.isNotNull("email");
int result = userMapper.delete(queryWrapper);
System.out.println("delete return count = " + result);
}
SQL:UPDATE user SET deleted=1 WHERE deleted=0 AND name IS NULL AND age >= ? AND email IS NOT NULL
(2) eq、ne
注意:seletOne返回的是一条实体记录,当出现多条时会报错
@Test
public void testSelectOne() {
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.eq("name", "Tom");
User user = userMapper.selectOne(queryWrapper);
System.out.println(user);
}
SELECT id,name,age,email,create_time,update_time,deleted,version FROM user WHERE deleted=0 AND name = ?
(3) between、notBetween
包含大小边界
@Test
public void testSelcecCount(){
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.between("age",20,30);
Integer integer = userMapper.selectCount(queryWrapper);
System.out.println("20<-->30之间" + integer + "人");
//SELECT COUNT(1) FROM user WHERE deleted=0 AND age BETWEEN ? AND ?
}
(4)allEq
@Test
public void testAllEq(){
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
Map<String, Object> map = new HashMap<>();
map.put("id",2L);
map.put("name","Jack");
map.put("age",20);
queryWrapper.allEq(map);
List<User> users = userMapper.selectList(queryWrapper);
users.forEach(System.err::println);
//SELECT id,name,age,email,create_time,update_time,version,deleted FROM user WHERE deleted=0 AND name = ? AND id = ? AND age = ?
}
(5)like、notLike、likeLeft、likeRight
selectMaps返回Map集合列表
@Test
public void testSelectMaps(){
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.notLike("name","e")
.likeRight("email","t");
List<Map<String, Object>> mapList = userMapper.selectMaps(queryWrapper);//返回值是Map列表
mapList.forEach(System.err::println);
/*
姓名中不含e且邮箱以e开头
SELECT id,name,age,email,create_time,update_time,version,deleted FROM user WHERE deleted=0 AND name NOT LIKE '%e%' AND email LIKE 't%'
{update_time=2019-08-15 09:31:29.0, deleted=0, create_time=2019-08-15 09:31:29.0, name=Jack, id=2, version=1, age=20, email=test2@baomidou.com}
{update_time=2019-08-15 09:31:29.0, deleted=0, create_time=2019-08-15 09:31:29.0, name=Tom, id=3, version=1, age=28, email=test3@baomidou.com}
{update_time=2019-08-15 09:31:29.0, deleted=0, create_time=2019-08-15 09:31:29.0, name=Sandy, id=4, version=1, age=21, email=test4@baomidou.com}
*/
}
(6)in、notIn、inSql、notinSql、exists、notExists
in、notIn:
notIn("age",{1,2,3})--->age not in (1,2,3)
notIn("age", 1, 2, 3)--->age not in (1,2,3)
inSql、notinSql:可以实现子查询
例: inSql("age", "1,2,3,4,5,6")--->age in (1,2,3,4,5,6)
例: inSql("id", "select id from table where id < 3")--->id in (select id from table where id < 3)
exits和notExists
EXISTS用于检查子查询是否至少会返回一行数据,该子查询实际上并不返回任何数据,而是返回值True或False
EXISTS 指定一个子查询,检测 行 的存在。
EXISTS(包括 NOT EXISTS )子句的返回值是一个BOOL值。
EXISTS内部有一个子查询语句(SELECT ... FROM...), 我将其称为EXIST的内查询语句。其内查询语句返回一个结果集。 EXISTS子句根据其内查询语句的结果集空或者非空,返回一个布尔值。
一种通俗的可以理解为:将外查询表的每一行,代入内查询作为检验,如果内查询返回的结果取非空值,则EXISTS子句返回TRUE,
这一行行可作为外查询的结果行,否则不能作为结果。
@Test
public void testSelectObjs(){
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
// queryWrapper.in("id",1,2,3,4);//SELECT id,name,age,email,create_time,update_time,version,deleted FROM user WHERE deleted=0 AND id IN (?,?,?,?)
// SELECT id,name,age,email,create_time,update_time,version,deleted FROM user WHERE deleted=0 AND id IN (select id from user where id < 3)
// queryWrapper.inSql("id","select id from user where id < 3");
// List<Object> objects = userMapper.selectObjs(queryWrapper);//返回值是Object列表
// objects.forEach(System.err::println);
// SELECT id,name,age,email,create_time,update_time,version,deleted FROM user WHERE deleted=0 AND EXISTS (select id from user where age = 2)
//当exists内的子查询值(非空)时返回true当无值为空(null)时返回false
queryWrapper.exists("select id from user where age = 2");
List<Object> objects = userMapper.selectObjs(queryWrapper);
objects.forEach(System.err::println);
}
(7)or、and
注意:这里使用的是 UpdateWrapper
不调用or则默认为使用 and 连
@Test
public void testUpdateOrAnd(){
//本例修改后其版本号为改变故此修改不合理
//修改或其他改变数据值得操作均需要携带version值
//修改值
User user = new User();
user.setVersion(1);
user.setAge(99);
user.setName("Andy");
//修改条件
UpdateWrapper<User> updateWrapper = new UpdateWrapper<>();
updateWrapper.like("name","d")
.or()
.between("age",98,100);
int update = userMapper.update(user, updateWrapper);
System.out.println(update + "行被修改");
/*
UPDATE user SET name='Andy', age=99, update_time='2019-08-15 16:32:53', version=2 WHERE deleted=0 AND name LIKE '%d%' OR age BETWEEN 98 AND 100 AND version = 1
*/
}
(8)嵌套or、嵌套and
这里使用了lambda表达式,or中的表达式最后翻译成sql时会被加上圆括号
@Test
public void testUpdateLambdaOrAnd(){
//本例修改后其版本号为改变故此修改不合理
//修改或其他改变数据值得操作均需要携带version值
//修改值
User user = new User();
user.setVersion(1);
user.setAge(99);
user.setName("Andy");
//修改条件
UpdateWrapper<User> updateWrapper = new UpdateWrapper<>();
updateWrapper.like("name","a")
.or(i->i.eq("name","苏洵").ne("age",20));
int update = userMapper.update(user, updateWrapper);
System.out.println(update + "行被修改");
/*
UPDATE user SET name='Andy', age=99, update_time='2019-08-15 16:47:02', version=2 WHERE deleted=0 AND name LIKE '%a%' OR ( name = '苏洵' AND age <> 20 ) AND version = 1
*/
}
(9) orderBy、orderByDesc、orderByAsc
@Test
public void testSelectListOrderBy(){
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.orderByDesc("id","age");
List<User> users = userMapper.selectList(queryWrapper);
users.forEach(System.err::println);
/*
SELECT id, name, age, email, create_time,update_time, version, deleted FROM user WHERE deleted=0 ORDER BY id DESC , age DESC
*/
}
(10) last
直接拼接到 sql 的最后
注意: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
@Test
public void testSelectListLast(){
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
//SELECT id,name,age,email,create_time,update_time,version,deleted FROM user WHERE deleted=0 limit 1,2
queryWrapper.last("limit 1,2");
List<User> users = userMapper.selectList(queryWrapper);
users.forEach(System.err::println);
}
(11) 指定要查询的列
@Test
public void testSelectListColumn(){
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.select("name","age","id");
List<User> users = userMapper.selectList(queryWrapper);
users.forEach(System.err::println);
/*
SELECT name, age, id FROM user WHERE deleted=0
*/
}
12、set、setSql
最终的sql会合并 user.setAge(),以及 userUpdateWrapper.set() 和 setSql() 中 的字段
@Test
public void testUpdateSet(){
//修改值
User user = new User();
user.setVersion(3);
user.setAge(1099);
//修改条件
UpdateWrapper<User> updateWrapper = new UpdateWrapper<>();
updateWrapper.like("name","大")
.set("name","王大强")
.setSql("email='wang@daniel.com'");
int update = userMapper.update(user, updateWrapper);
System.out.println(update + "行被修改");
/*
UPDATE user SET age=1099,update_time='2019-08-15 17:24:28', version=4,name='王大强', email='wang@daniel.com' WHERE deleted=0 AND name LIKE '%大%'
AND version = 3
*/
}
mybatisplus官网对条件构造器的描述也很详细可以去看看