mybatis操作mysql的奇淫技巧总结（代码库）

1、添加公共sql代码段

使用<sql> 和 <include> 标签

<sql id="userSubassemblyRecordParam">
    id, user_id, lesson_id, subassembly_id, record_id, course_id, teacher_id, status, create_time, update_time
</sql>

<select id="listUserSubassemblyRecordByParam" resultMap="userSubassemblyRecordMap">
    SELECT
      <include refid="userSubassemblyRecordParam"/>
    FROM
      rel_user_subassembly_record
</select>

 

2、动态更新

选择更新，为空则不更新，在<set> 标签里添加 <if> 标签，不需要考虑<if> 标签里的逗号 

<update id="updateSchoolLevel" parameterType="com.ajz.course.entity.School">
    UPDATE
      school
    <set>
        <if test="gaokao != null">
            gaokao = #{gaokao},
        </if>
        <if test="contest != null">
            contest = #{contest},
        </if>
        <if test="independent != null &amp;&amp; independent != 0">
            independent = #{independent},
        </if>
    </set>
    WHERE
      id = #{id}
</update>

  

3、批量动态更新

在2 的基础上添加<trim> 和<foreach>标签 

<update id="updateCourseRateStateByCourseList">
    UPDATE
        course
    <trim prefix="set" suffixOverrides=",">
        <trim prefix="rate_state =case" suffix="end,">
            <foreach collection="list" item="item" index="index">
                <if test="item.rateState!=null">
                    when id=#{item.id} then #{item.rateState}
                </if>
            </foreach>
        </trim>
        <trim prefix="name =case" suffix="end,">
            <foreach collection="list" item="item" index="index">
                <if test="item.name!=null">
                    when id=#{item.id} then #{item.name}
                </if>
            </foreach>
        </trim>
    </trim>
    WHERE
    <foreach collection="list" separator="or" item="item" index="index" >
        id=#{item.id}
    </foreach>
</update>

  

4、动态插入

选择插入，为空则不插入，在key 和value 两个部分都需要判断

<insert id="insertSyllabus" useGeneratedKeys="true" keyProperty="syllabusId"
        parameterType="com.ajz.course.entity.Syllabus">
    INSERT INTO
      syllabus
    <trim prefix="(" suffix=")" suffixOverrides=",">
        course_id,
        <if test="startTime != null">
            start_time,
        </if>
        <if test="endTime != null">
            end_time,
        </if>
    </trim>
    <trim prefix="values (" suffix=")" suffixOverrides=",">
        #{courseId},
        <if test="startTime != null">
            #{startTime},
        </if>
        <if test="endTime != null">
            #{endTime}
        </if>
    </trim>
</insert>

 

5、批量插入

只在VALUES 部分循环

<insert id="insertTimetableList" parameterType="java.util.List">
    INSERT INTO
        timetable (user_id, user_type, lesson_id, lesson_time, watch_state, status)
    VALUES
    <foreach collection="list" item="item" index="index" separator=",">
        (#{item.userId},
        #{item.userType},
        #{item.lessonId},
        #{item.lessonTime},
        #{item.watchState},
        #{item.status})
    </foreach>
</insert>

 

6、数据库根据主键自己选择插入还是更新，insertOrUpdate 

相当于 jpa的 merge，关键在于唯一索引，也可以是主键，关键字：ON DUPLICATE KEY UPDATE

<!--user_id, user_type, lesson_id 三个字段建立了联合唯一索引-->
<insert id="insertOrUpdateTimetable" useGeneratedKeys="true" keyProperty="id" parameterType="com.ajz.course.entity.Timetable">
    INSERT INTO
        timetable (user_id, user_type, lesson_id, lesson_time, watch_state, status)
    VALUES (#{userId},
        #{userType},
        #{lessonId},
        #{lessonTime},
        #{watchState},
        #{status})
        ON DUPLICATE KEY UPDATE
            lesson_time = #{lessonTime}, watch_state = #{watchState}, status = #{status}
</insert>

 

7、批量insertOrUpdate 

在5和6的基础上实现，注意 ON DUPLICATE KEY UPDATE 后面的 VALUES，是数据库的字段，而不是实体的字段， admin_name = VALUES(admin_name)

<insert id="insertOrUpdateStatSchoolHome" useGeneratedKeys="true" keyProperty="id" parameterType="com.ajz.course.entity.StatSchoolHome">
    INSERT INTO
        stat_school_home (sid,
        name,
        admin_name,
        type_key,
        status)
    VALUES
    <foreach collection="list" item="item" index="index" open="" close="" separator=",">
        (#{item.sid},
        #{item.name},
        #{item.adminName},
        #{item.typeKey},
        #{item.status})
    </foreach>
    ON DUPLICATE KEY UPDATE
        name = VALUES(name),
        admin_name = VALUES(admin_name),
        type_key = VALUES(type_key),
        status = VALUES(status)
</insert>

 

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