后端-框架-MyBatis-动态SQL-trim

后端-框架-MyBatis-动态SQL-trim

trim(where, set)互相替换

<trim prefix="?" prefixOverrides="? | ? " suffix="?" suffixOverrides="? | ?"><trim>

where标签

<select id="getUserList" resultMap="getUserList">
    	select user.* from smbms_user as user
        <!-- 通过where标签动态剔除拼接的and和or -->
    	<where>
    		user.userRole=role.id
            <!-- 通过if标签防止输入null导致无查询结果 -->
    		<if test="userName != null and userName != '' ">
    			and user.userName like Concat('%',#{userName},'%')
    		</if>
    		<if test="userRole != null">
    			and user.userRole=#{userRole}
    		</if>
    	</where>
    </select>

trim替代where

<select id="getUserList" resultMap="getUserList">
    	select user.* from smbms_user as user
        <!-- 通过trim标签动态剔除拼接的and和or -->
    	<trim prefix="Where" prefixOverrides="and | or ">
    		user.userRole=role.id
    		<if test="userName != null and userName != '' ">
    			and user.userName like Concat('%',#{userName},'%')
    		</if>
    		<if test="userRole != null">
    			and user.userRole=#{userRole}
    		</if>
    	</trim>
    </select>

set标签

<update id="updateUser" parameterType="User">
    	update smbms_user
        <!-- 使用set标签动态更新,并自动剔除, -->
    	<set>
            <!-- 通过if标签防止输入null导致更新失败 -->
    		<if test="userName != null">userName = #{userName},</if>
    	    <if test="modifyBy != null">modifyBy = #{modifyBy},</if>
    		<if test="modifyDate != null">modifyDate = #{modifyDate},</if>
    	</set>
    	where id = #{id}
    </update>

trim替代set

<update id="updateUser" parameterType="User">
    	update smbms_user
    	<trim prefix="set" suffixOverrides="," suffix="where id = #{id}">
    		<if test="userName != null">userName = #{userName},</if>
    		<if test="modifyBy != null">modifyBy = #{modifyBy},</if>
    		<if test="modifyDate != null">modifyDate = #{modifyDate},</if>
    	</trim>
    </update>