Java笔记之Mybatis(三):模糊查询

1.t_student表新增数据

USE keeper;
INSERT INTO `t_student` VALUES (null, '张无忌', 25);
INSERT INTO `t_student` VALUES (null, '张三丰', 100);
INSERT INTO `t_student` VALUES (null, '赵云', 27);
INSERT INTO `t_student` VALUES (null, '赵三', 24);

2.修改Student.xml

<?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">
<mapper namespace="com.mybatis.demo.pojo">
    <!-- 查询所有的Student信息 -->
    <select id="getAllStudent" resultType="Student">
        select 
            student_id,
            student_name,
            student_age
        from 
            t_student
    </select>
    
    <!-- 根据ID查询Student的信息 -->
    <select id="getStudentById" parameterType="int" resultType="Student">
        select 
            * 
        from 
            t_student 
        where 
            student_id=#{value}
    </select>
    
    <!-- 新增Student信息 -->
    <insert id="addStudent" parameterType="Student">
        insert 
        into 
            t_student 
        values(
            null,
            #{studentName},
            #{studentAge}
        )
    </insert>
    
    <!-- 根据ID删除指定的Student信息 -->
    <delete id="deleteStudentById" parameterType="int">
        delete 
            from t_student 
        where 
            student_id=#{value}
    </delete>
    
    <!-- 根据ID更新Student信息 -->
    <update id="updateStudentById" parameterType="Student">
        update 
            t_student 
        set 
            student_name=#{studentName},
            student_age=#{studentAge} 
        where 
            student_id=#{studentId}
    </update>
    
    <!-- 根据学生名字模糊查询学生信息 -->
    <select id="getStudentByName" parameterType="string" resultType="Student">
        select 
            * 
        from 
            t_student 
        where 
            student_name like concat('%',#{value},'%')
    </select>
</mapper>

3.在com.mybatis.demo.test下新建MybatisTest2类

package com.mybatis.demo.test;

import java.io.IOException;
import java.io.InputStream;
import java.util.List;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import com.mybatis.demo.pojo.Student;

public class MybatisTest2 {

    public static void main(String[] args) throws IOException {
        //加载mybatis的配置文件
        InputStream inputStream = Resources.getResourceAsStream("mybatisConfig.xml");
        //获取SqlSessionFactory对象
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        //使用SqlSessionFactory对象创建SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession();
        List<Student> students1 = sqlSession.selectList("getStudentByName", "张");
        for (Student student : students1) {
            System.out.println(student.getStudentId()+"\t"+student.getStudentName()+"\t"+student.getStudentAge());
        }
        System.out.println("======华丽的分割线======");
        List<Student> students2 = sqlSession.selectList("getStudentByName", "三");
        for (Student student : students2) {
            System.out.println(student.getStudentId()+"\t"+student.getStudentName()+"\t"+student.getStudentAge());
        }
    }

}

4.运行MybatisTest2类,结果如下:

7    张无忌    25
8    张三丰    100
======华丽的分割线======
8    张三丰    100
10    赵三    24

5.总结

　　(1).mysql数据库中模糊查询使用concat函数,将%与查询参数拼接起来,例如该例中的查询条件student_name like concat('%',#{value},'%')

　　(2).oracle数据库中则使用||连接%与查询参数,例如本例中的查询条件将改成student_name like '%'||#{value}||'%'