05-curd(代码片段)

<?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="xxx">
    <insert id="insertStudent">
        insert into student(name,age,score) values(#name, #age, #score)
    </insert>
    
    <insert id="insertStudentCatchId">
        insert into student(name,age,score) values(#name, #age, #score)
        <selectKey resultType="int" keyProperty="id" order="AFTER">
            <!-- select @@identity -->
            select last_insert_id()
        </selectKey>
    </insert>
    
    <!-- 当动态参数类型为基本数据类型或String时，#的作用仅仅是个占位符，其中填写什么内容都可以
         当动态参数类型为自定义类型的对象时，#中填写的是该对象的属性名
     -->
    <delete id="deleteById">
        delete from student where id=#xxx
    </delete>
    
    <update id="updateStudent">
        update student set name=#name, age=#age, score=#score where id=#id
    </update>
    
    <!-- resultType与resultMap指的是查询出的每一条记录所要封闭的对象类型，并非查询的结果集类型 -->
    <select id="selectAllStudent" resultType="Student">
        select id,name,age,score from student
    </select>
    
    <select id="selectStudentById" resultType="Student">
        select id,name,age,score from student where id=#ooo
    </select>
    
    <select id="selectStudentsByName" resultType="Student">
        <!-- select * from student where name like ‘%张%‘ -->
        select id,name,age,score from student where name like ‘%‘ #jjj ‘%‘
        <!-- select id,name,age,score from student where name like concat(‘%‘, #jjj, ‘%‘) -->
        <!-- select id,name,age,score from student where name like ‘%$value%‘ -->
    </select>
    
    <select id="selectStudentsByCondition" resultType="Student">
        select id,name,age,score from student where name like ‘%‘ #name ‘%‘ and  age &lt; #age
    </select>
    
    <select id="selectStudentsByCondition2" resultType="Student">
        <!-- select id,name,age,score from student where name like ‘%‘ #cname ‘%‘ and  age &lt; #cage -->
        select id,name,age,score from student where name like ‘%‘ #stu1.name ‘%‘ and  age &lt; #stu2.age
    </select>
    
    <!-- 总结
        #中可写填写什么内容：
        1）参数对象的属性
        2）任意内容，参数对象为基本数据类型或String时，起占位符作用
        3）map的key
        4）map的key的属性，当map的key为对象时
     -->
    
    
</mapper>