mybatis的selectKey功用

引言（需求）

 

         需求來了，聽好了。

         車主故事錄入（車主分享自己的購車經歷），按照長城的需求來說，一個車主只能分享一次故事，如果在進入

個人中心裏，需判斷是否有車主故事了，如果有直接修改，沒有則添加。之前蠢蠢的，做個 if 判斷嘛，有記錄就修

改，沒有記錄就添加，但是一整理的時候發現重複代碼太多。後來想到咱們用Hibernate的時候不是有個方法交

UpdateorSave嗎，網上一查，mybatis果然可以實現！

直接上代碼！

        

<!-- 車主故事錄入 -->
<insert id="saveCarStory" useGeneratedKeys="true" keyProperty="memberOwnerStoryId" parameterType="com.ec.model.carStory.MemberOwnerStory">
    <!-- 查看是否存在memberid,如果存在及更新，否則插入 -->
    <selectKey keyProperty="count" resultType="int" order="BEFORE">
        select count(*) as count from member_owner_story where MEMBER_ID = #{memberId,jdbcType=INTEGER}
    </selectKey>

    <!-- 如果大於0則更新 -->
    <if test="count>0">
        update member_owner_story set
        STORY_TOPIC=#{storyTopic,jdbcType=VARCHAR},
        STORY_CONTENT=#{storyContent,jdbcType=VARCHAR},
        ADD_TIME=#{addTime,jdbcType=VARCHAR},
        SHOW_CARTYPE=#{showCartype,jdbcType=VARCHAR},
        SAVE_MODE=#{saveMode,jdbcType=VARCHAR}
        where MEMBER_ID = #{memberId,jdbcType=INTEGER}
    </if>

    <!-- 如果等於0則保存 -->
    <if test="count==0">
        insert into member_owner_story
        <trim prefix="(" suffix=")" suffixOverrides="," >
            <if test="memberId != null ">MEMBER_ID,</if>
            <if test="productId != null ">PRODUCT_ID,</if>
            <if test="catalogId != null ">CATALOG_ID,</if>
            <if test="storyTopic != null ">STORY_TOPIC,</if>
            <if test="storyContent != null ">STORY_CONTENT,</if>
            <if test="showTime != null ">SHOW_TIME,</if>
            <if test="isAudit != null ">IS_AUDIT,</if>
            <if test="auditUserId != null ">AUDIT_USER_ID,</if>
            <if test="auditTime != null ">AUDIT_TIME,</if>
            <if test="isDelete != null ">IS_DELETE,</if>
            <if test="addUserId != null ">ADD_USER_ID,</if>
            <if test="addTime != null ">ADD_TIME,</if>
            <if test="editUserId != null ">EDIT_USER_ID,</if>
            <if test="editTime != null ">EDIT_TIME,</if>
            <if test="noAuditReason != null ">NO_AUDIT_REASON,</if>
            <if test="praiseNum != null ">PRAISE_NUM,</if>
            <if test="showCartype != null ">SHOW_CARTYPE,</if>
            <if test="saveMode != null ">SAVE_MODE,</if>
        </trim>
        <trim prefix="values (" suffix=")" suffixOverrides="," >
            <if test="memberId != null ">#{memberId,jdbcType=INTEGER},</if>
            <if test="productId != null ">#{productId,jdbcType=INTEGER},</if>
            <if test="catalogId != null ">#{catalogId,jdbcType=INTEGER},</if>
            <if test="storyTopic != null ">#{storyTopic,jdbcType=VARCHAR},</if>
            <if test="storyContent != null ">#{storyContent,jdbcType=VARCHAR},</if>
            <if test="showTime != null ">#{showTime,jdbcType=VARCHAR},</if>
            <if test="isAudit != null ">#{isAudit,jdbcType=VARCHAR},</if>
            <if test="auditUserId != null ">#{auditUserId,jdbcType=VARCHAR},</if>
            <if test="auditTime != null ">#{auditTime,jdbcType=VARCHAR},</if>
            <if test="isDelete != null ">#{isDelete,jdbcType=VARCHAR},</if>
            <if test="addUserId != null ">#{addUserId,jdbcType=VARCHAR},</if>
            <if test="addTime != null ">#{addTime,jdbcType=VARCHAR},</if>
            <if test="editUserId != null ">#{editUserId,jdbcType=VARCHAR},</if>
            <if test="editTime != null ">#{editTime,jdbcType=VARCHAR},</if>
            <if test="noAuditReason != null ">#{noAuditReason,jdbcType=VARCHAR},</if>
            <if test="praiseNum != null ">#{praiseNum,jdbcType=VARCHAR},</if>
            <if test="showCartype != null ">#{showCartype,jdbcType=VARCHAR},</if>
            <if test="saveMode != null ">#{saveMode,jdbcType=VARCHAR},</if>
        </trim>
    </if>

</insert>

       先根據memberId判斷是否有車主故事的相關記錄，返回count，如果有數據（count>0），則說明車主之前錄入過

車主故事，所以直接進行更新就Ok；否則進行插入操作。

       這樣就實現了更新和插入的操作了哦~~~很簡單吧~~