0
点赞
收藏
分享

微信扫一扫

【Mybatis学习总结六】动态SQL与模糊查询

IT程序员 2022-11-22 阅读 76


六、动态SQL与模糊查询

学数据库的时候有学过模糊查询。如:根据姓名模糊匹配和指定年龄区间 来查询用户信息:

SQL语句可以这样来写:

SELECT * FROM d_user WHERE name like '%m%' AND age between 12 AND 18

现在在Mbatis中进行实现:

1 准备表和数据:


create table d_user(
id int primary key auto_increment,
name varchar(10),
age int(3)
);
insert into d_user(name,age) values('Tom',12);
insert into d_user(name,age) values('Bob',13);


2 查询条件实体类:ConditionUser.java


package com.mybatis.entities;

public class ConditionUser {

private String name;
private int minAge;
private int maxAge;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getMinAge() {
return minAge;
}
public void setMinAge(int minAge) {
this.minAge = minAge;
}
public int getMaxAge() {
return maxAge;
}
public void setMaxAge(int maxAge) {
this.maxAge = maxAge;
}
public ConditionUser(String name, int minAge, int maxAge) {
super();
this.name = name;
this.minAge = minAge;
this.maxAge = maxAge;
}
public ConditionUser() {
super();
}


}

3


package com.mybatis.entities;

public class User {

private int id;
private String name;
private int age;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public User(int id, String name, int age) {
super();
this.id = id;
this.name = name;
this.age = age;
}
public User() {
super();
}
@Override
public String toString() {
return "User [id=" + id + ", name=" + name + ", age=" + age + "]";
}

}


4 userMapper2.xml映射文件:


<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!--
5 模糊查询:根据条件查询用户(姓名模糊匹配,年龄在指定的最小值和最大值之间)
SQL:select * from d_user where name like '%o%' and age>=13 and age<=18
-->
<!--定义操作 classes 表的sql 映射文件:userMapper2.xml -->
<mapper namespace="com.mybatis.test6.userMapper2">

<select id="getUser" parameterType="User"
resultType="User">

select * from d_user where age between #{minAge} and #{maxAge}

<!--当输入的name!=null 时就执行下面的语句 -->
<if test=' name != "%null%" '>
and name like #{name}
</if>

</select>

</mapper>


5

package com.mybatis.test6;

import java.util.List;

import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import com.mybatis.entities.ConditionUser;
import com.mybatis.entities.User;

public class Test6 {

@Test
public void test() {

SqlSession session= MybatisUtils.getSqlSessionFactory().openSession();


String statement = "com.mybatis.test6.userMapper2.getUser";

//模拟从网页输入的三个参数,将其封装到ConditionUser中
String name = "o";
int minAge = 13;
int maxAge = 18;
ConditionUser parameter=new ConditionUser("%"+name+"%", minAge, maxAge);

List<User> users= session.selectList(statement, parameter);
System.out.println(users);
session.close();
}

}



举报

相关推荐

0 条评论