mybatis的快速入门以及spring boot整合mybatis(二)
需要用到的SQL脚本:
CREATE TABLE dept (
id int unsigned PRIMARY KEY AUTO_INCREMENT COMMENT 'ID, 主键',
name varchar(10) NOT NULL UNIQUE COMMENT '部门名称',
create_time datetime DEFAULT NULL COMMENT '创建时间',
update_time datetime DEFAULT NULL COMMENT '修改时间'
) COMMENT '部门表';
INSERT INTO dept VALUES (1,'学工部','2023-09-25 09:47:40','2023-09-25 09:47:40'),
(2,'教研部','2023-09-25 09:47:40','2023-10-09 15:17:04'),
(3,'咨询部2','2023-09-25 09:47:40','2023-11-30 21:26:24'),
(4,'就业部','2023-09-25 09:47:40','2023-09-25 09:47:40'),
(5,'人事部','2023-09-25 09:47:40','2023-09-25 09:47:40'),
(15,'行政部','2023-11-30 20:56:37','2023-11-30 20:56:37');
create table emp(
id int unsigned primary key auto_increment comment 'ID,主键',
username varchar(20) not null unique comment '用户名',
password varchar(50) default '123456' comment '密码',
name varchar(10) not null comment '姓名',
gender tinyint unsigned not null comment '性别, 1:男, 2:女',
phone char(11) not null unique comment '手机号',
job tinyint unsigned comment '职位, 1 班主任, 2 讲师 , 3 学工主管, 4 教研主管, 5 咨询师',
salary int unsigned comment '薪资',
image varchar(300) comment '头像',
entry_date date comment '入职日期',
dept_id int unsigned comment '部门ID',
create_time datetime comment '创建时间',
update_time datetime comment '修改时间'
) comment '员工表';
INSERT INTO emp VALUES
(1,'shinaian','123456','施耐庵',1,'13309090001',4,15000,'5.png','2000-01-01',2,'2023-10-20 16:35:33','2023-11-16 16:11:26'),
(2,'songjiang','123456','宋江',1,'13309090002',2,8600,'01.png','2015-01-01',2,'2023-10-20 16:35:33','2023-10-20 16:35:37'),
(3,'lujunyi','123456','卢俊义',1,'13309090003',2,8900,'01.png','2008-05-01',2,'2023-10-20 16:35:33','2023-10-20 16:35:39'),
(4,'wuyong','123456','吴用',1,'13309090004',2,9200,'01.png','2007-01-01',2,'2023-10-20 16:35:33','2023-10-20 16:35:41'),
(5,'gongsunsheng','123456','公孙胜',1,'13309090005',2,9500,'01.png','2012-12-05',2,'2023-10-20 16:35:33','2023-10-20 16:35:43'),
(6,'huosanniang','123456','扈三娘',2,'13309090006',3,6500,'01.png','2013-09-05',1,'2023-10-20 16:35:33','2023-10-20 16:35:45'),
(7,'chaijin','123456','柴进',1,'13309090007',1,4700,'01.png','2005-08-01',1,'2023-10-20 16:35:33','2023-10-20 16:35:47'),
(8,'likui','123456','李逵',1,'13309090008',1,4800,'01.png','2014-11-09',1,'2023-10-20 16:35:33','2023-10-20 16:35:49'),
(9,'wusong','123456','武松',1,'13309090009',1,4900,'01.png','2011-03-11',1,'2023-10-20 16:35:33','2023-10-20 16:35:51'),
(10,'linchong','123456','林冲',1,'13309090010',1,5000,'01.png','2013-09-05',1,'2023-10-20 16:35:33','2023-10-20 16:35:53'),
(11,'huyanzhuo','123456','呼延灼',1,'13309090011',2,9700,'01.png','2007-02-01',2,'2023-10-20 16:35:33','2023-10-20 16:35:55'),
(12,'xiaoliguang','123456','小李广',1,'13309090012',2,10000,'01.png','2008-08-18',2,'2023-10-20 16:35:33','2023-10-20 16:35:57'),
(13,'yangzhi','123456','杨志',1,'13309090013',1,5300,'01.png','2012-11-01',1,'2023-10-20 16:35:33','2023-10-20 16:35:59'),
(14,'shijin','123456','史进',1,'13309090014',2,10600,'01.png','2002-08-01',2,'2023-10-20 16:35:33','2023-10-20 16:36:01'),
(15,'sunerniang','123456','孙二娘',2,'13309090015',2,10900,'01.png','2011-05-01',2,'2023-10-20 16:35:33','2023-10-20 16:36:03'),
(16,'luzhishen','123456','鲁智深',1,'13309090016',2,9600,'01.png','2010-01-01',2,'2023-10-20 16:35:33','2023-10-20 16:36:05'),
(17,'liying','12345678','李应',1,'13309090017',1,5800,'01.png','2015-03-21',1,'2023-10-20 16:35:33','2023-10-20 16:36:07'),
(18,'shiqian','123456','时迁',1,'13309090018',2,10200,'01.png','2015-01-01',2,'2023-10-20 16:35:33','2023-10-20 16:36:09'),
(19,'gudasao','123456','顾大嫂',2,'13309090019',2,10500,'01.png','2008-01-01',2,'2023-10-20 16:35:33','2023-10-20 16:36:11'),
(20,'ruanxiaoer','123456','阮小二',1,'13309090020',2,10800,'01.png','2018-01-01',2,'2023-10-20 16:35:33','2023-10-20 16:36:13'),
(21,'ruanxiaowu','123456','阮小五',1,'13309090021',5,5200,'01.png','2015-01-01',3,'2023-10-20 16:35:33','2023-10-20 16:36:15'),
(22,'ruanxiaoqi','123456','阮小七',1,'13309090022',5,5500,'01.png','2016-01-01',3,'2023-10-20 16:35:33','2023-10-20 16:36:17'),
(23,'ruanji','123456','阮籍',1,'13309090023',5,5800,'01.png','2012-01-01',3,'2023-10-20 16:35:33','2023-10-20 16:36:19'),
(24,'tongwei','123456','童威',1,'13309090024',5,5000,'01.png','2006-01-01',3,'2023-10-20 16:35:33','2023-10-20 16:36:21'),
(25,'tongmeng','123456','童猛',1,'13309090025',5,4800,'01.png','2002-01-01',3,'2023-10-20 16:35:33','2023-10-20 16:36:23'),
(26,'yanshun','123456','燕顺',1,'13309090026',5,5400,'01.png','2011-01-01',3,'2023-10-20 16:35:33','2023-11-08 22:12:46'),
(27,'lijun','123456','李俊',1,'13309090027',2,6600,'8.png','2004-01-01',2,'2023-10-20 16:35:33','2023-11-16 17:56:59'),
(28,'lizhong','123456','李忠',1,'13309090028',5,5000,'6.png','2007-01-01',3,'2023-10-20 16:35:33','2023-11-17 16:34:22'),
(30,'liyun','123456','李云',1,'13309090030',NULL,NULL,'01.png','2020-03-01',NULL,'2023-10-20 16:35:33','2023-10-20 16:36:31'),
(36,'linghuchong','123456','令狐冲',1,'18809091212',2,6800,'1.png','2023-10-19',2,'2023-10-20 20:44:54','2023-11-09 09:41:04');
员工列表查询:
基本查询:
需求:查询员工信息,并查询出部门名称。(涉及到的表:emp,dept)
基本查询的SQL语句:
select e.*, d.name deptName from emp e left join dept d on e.dept_id = d.id ;
?查询结果的封装,需要保证查询返回的字段名与类中的属性名保持一致。
在empController编写查询全部的方法,调用service层
?
/**
* 基本查询
* @return
*/
@GetMapping("/list")
public Result getList(){
List<Emp> empList = empService.list();
return Result.success(empList);
}
编写 empService
List<Emp> list();
编写empServiceImpl实现类:
@Override
public List<Emp> list() {
return empMapper.getList();
}
编写empMapper
?
@Select("select e.*,d.name deptName from emp e left join dept d on e.dept_id = d.id")
List<Emp> getList();
在Apifox里面测试:
分页查询:
原始的分页查询:
原始的分页查询会执行两条SQL语句
select * from emp e left join dept d on e.dept_id = d.id limit; 分页查询
select count(*)??from emp e left join dept d e.dept_id = d.id;? 查询数量
前端如何传递数据给后端:
当前页面:page
每页显示记录数: pageSize?
在empController编写方法:
@GetMapping
public Result list(Integer page,Integer pageSize){
PageBean pageBean = empService.getList(page,pageSize);
return Result.success(pageBean);
}
编写empService接口:
?
/**
* 分页查询
* @param page
* @param pageSize
* @return
*/
PageBean getList(Integer page, Integer pageSize);
编写empServiceImpl实现类:
@Override
public PageBean getList(Integer page, Integer pageSize) {
//计算起始索引
Integer start = (page - 1) * pageSize;
//查询全部数据
List<Emp> empList = empMapper.list(start,pageSize);
//查询总的记录数
Long count = empMapper.getCount();
return new PageBean(count,empList);
}
编写empMapper接口:
@Select("select e.*,d.name deptName from emp e left join dept d on e.dept_id = d.id limit #{start},#{pageSize}")
List<Emp> list(Integer start, Integer pageSize);
@Select("select count(*) from emp left join dept on emp.dept_id = dept.id")
Long getCount();
后端给前端返回的数据:
数据列表: List rows;
总记录数: Long total;
PageHelper分页插件:
PageHelper 是第三方提供的在mybatis框架中用来实现分页的插件,用来简化分页操作,提高开发效率。?
PageHelper实现机制:
?
使用步骤:
- ?引入PageHelper的依赖
- 定义Mapper接口的查询方法(无需考虑分页)
- 在Service方法中实现分页查询?
引入依赖:
<!-- 分页插件-->
<dependency>
<groupId>com.github.pagehelper</groupId>
<artifactId>pagehelper-spring-boot-starter</artifactId>
<version>1.4.7</version>
</dependency>
?编写 EmpController层:
@GetMapping
public Result list(Integer page,Integer pageSize){
PageBean pageBean = empService.getList(page,pageSize);
return Result.success(pageBean);
}
编写EmpService接口:
?
PageBean getList(Integer page, Integer pageSize);
编写 EmpServiceImpl实现类:
/**
* PageHeloer分页查询
* @param page
* @param pageSize
* @return
*/
@Override
public PageBean getList(Integer page, Integer pageSize) {
PageHelper.startPage(page,pageSize);
List<Emp> empList = empMapper.PageList();
Page<Emp> emps = (Page<Emp>) empList;
return new PageBean(emps.getTotal(),emps.getResult());
}
编写EmpMapper接口:
/**
* pageHelper分页查询
*/
@Select("select e.*,d.name deptName from emp e left join dept d on e.dept_id = d.id ")
List<Emp> PageList();
?调用Apifox测试:
控制台:
使用PageHelper分页插件的注意事项:
- SQL语句结尾不要加分号(;)
- PageHelper只会对紧跟在其后的第一条SQL语句进行分页处理
测试 在SQL语句结尾加分号(;)
<select id="wherePage" resultType="com.sde.pojo.Emp">
select e.*,d.name deptName from emp e left join dept d on e.dept_id = d.id
<where>
<if test="name != null and name != ''">
e.name like concat('%',#{name},'%')
</if>
<if test="gender != null">
and e.gender = #{gender}
</if>
<if test="begin != null and end != null">
and e.entry_date between #{begin} and #{end}
</if>
</where>
order by e.update_time desc;
</select>
然后启动项目运行在Apifox测试:
?
控制台输出:
因为我们在后面加了分号,所以在最后执行 limit分页的时候,前面多了一个分号,所以SQL语句就报错了。
解决办法:去掉SQL语句后面最后面的一个分号(;)?
2,测试PageHelper之后执行,紧跟在后面的第一条SQL语句进行处理
?我把empMapper.PageList();方法复制一行写在下面,然后把它执行的SQL语句,强转成page,最后return出去。
在ApiFox里面测试:
?看看控制台:
条件分页查询:
- select * from emp e ... where e.name like ?
- select * from emp e ... where e.gender = ?
- select * from emp e ... where e.name like ? and e.gender = ?
?接收请求参数:
接收条件分页查询的请求参数:GET /emps?name=张&gender=1&begin=2007-09-01&end=2022-09-01&page=1&pageSize=1
通过方法多形参,接收多参数:
就是前端在传递条件分页数据时,有多少参数就,在这个方法里面定义多少形参。
编写 EmpController
/**
* 条件分页查询--多参数接收
* @param
* @param
* @return
*/
@GetMapping("/getByList")
public Result list(String name,Integer gender,
@DateTimeFormat(pattern = "yyyy-MM-dd") LocalDate begin,
@DateTimeFormat(pattern = "yyyy-MM-dd") LocalDate end,
@RequestParam(defaultValue = "1") Integer page,
@RequestParam(defaultValue = "10") Integer pageSize){
log.info("接收到前端传递来的参数:{},{},{},{},{},{}",name,gender,begin,end,page,pageSize);
PageBean pageBean = empService.moreQuery(name,gender,begin,end,page,pageSize);
return Result.success(pageBean);
}
编写EmpService接口:
PageBean moreQuery(String name, Integer gender, LocalDate begin, LocalDate end, Integer page, Integer pageSize);
编写 EmpServiceImpl实现类:
@Override
public PageBean moreQuery(String name, Integer gender, LocalDate begin, LocalDate end, Integer page, Integer pageSize) {
PageHelper.startPage(page,pageSize);
List<Emp> empList = empMapper.getByWhere(name,gender,begin,end);
Page p = (Page) empList;
return new PageBean(p.getTotal(),p.getResult());
}
编写 EmpMapper接口:
List<Emp> getByWhere(String name, Integer gender, LocalDate begin, LocalDate end);
EmpMapper.xml配置文件:
在Apifox里面测试:
场景:如果参数个数比较少,建议直接接收即可。 如果参数个数较多,不便于维护和管理
在Controller方法中,通过实体对象接收。
在Controller方法中通过实体对象封装多个参数。(实体属性与请求参数名保持一致)
前端的请求:
GET /emps?name=张&gender=1&begin=2007-09-01&end=2022-09-01&page=1&pageSize=10
?定义一个 EmpQuery的实体类:
@Data
public class EmpQuery {
private String name;
private Integer gender;
@DateTimeFormat(pattern = "yyyy-MM-dd")
private LocalDate begin;
@DateTimeFormat(pattern = "yyyy-MM-dd")
private LocalDate end;
private Integer page = 1;
private Integer pageSize = 10;
}
编写 EmpController
/**
* 条件分页查询用对象接收
* @param empQuery
* @return
*/
@GetMapping
public Result listQuery(EmpQuery empQuery){
log.info("接收到前端传递来的参数:{}",empQuery);
PageBean pageBean = empService.wherePage(empQuery);
return Result.success(pageBean);
}
编写EmpService接口:
/**
* 条件分页查询
* @param empQuery
* @return
*/
PageBean wherePage(EmpQuery empQuery);
EmpServiceImpl实现类:
/**
* 条件分页查询
* @param empQuery
* @return
*/
@Override
public PageBean wherePage(EmpQuery empQuery) {
//设置分压查询的参数
PageHelper.startPage(empQuery.getPage(), empQuery.getPageSize());
// 调用mapper接口,进行条件查询
List<Emp> empList = empMapper.wherePage(empQuery);
//强转为page类型
Page<Emp> page = (Page<Emp>) empList;
return new PageBean(page.getTotal(),page.getResult());
}
编写 EmpMapper接口:
/**
* 条件分页查询
* @param empQuery
* @return
*/
List<Emp> wherePage(EmpQuery empQuery);
EmpMapper.xml配置文件:
<select id="getByWhere" resultType="com.sde.pojo.Emp">
select e.*,d.name deptName from emp e left join dept d on e.dept_id = d.id
<where>
<if test="name != null and name != ''">
e.name like concat('%',#{name},'%')
</if>
<if test="gender != null">
and e.gender = #{gender}
</if>
<if test="begin != bull and end != null ">
and e.entry_date between #{begin} and #{end}
</if>
</where>
</select>
在Apifox里面测试:
接收时间日期的参数:
@LocalDateTime 这个注解,有一个pattern属性,可以指定接收前端的数据格式。
@LocalDateTime(pattern="yyyy-MM-dd")
where 标签的作用:
- 自动根据条件判定是否添加 where 关键字
- 可以去除掉第一个前面多余的and或or
本文来自互联网用户投稿,该文观点仅代表作者本人,不代表本站立场。本站仅提供信息存储空间服务,不拥有所有权,不承担相关法律责任。 如若内容造成侵权/违法违规/事实不符,请联系我的编程经验分享网邮箱:veading@qq.com进行投诉反馈,一经查实,立即删除!