mybatis xml写动态 sql where set 自动去除 ， and/or

源：http://limingnihao.iteye.com/blog/782190
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3.5 if + trim代替where/set标签

trim是更灵活的去处多余关键字的标签，他可以实践where和set的效果。



3.5.1trim代替where


Xml代码 收藏代码

<!-- 5.1 if/trim代替where(判断参数) - 将实体类不为空的属性作为where条件 --> 

 <select id="getStudentList_if_trim" resultMap="resultMap_studentEntity"> 

 SELECT ST.STUDENT_ID, 

 ST.STUDENT_NAME, 

 ST.STUDENT_SEX, 

 ST.STUDENT_BIRTHDAY, 

 ST.STUDENT_PHOTO, 

 ST.CLASS_ID, 

 ST.PLACE_ID 

 FROM STUDENT_TBL ST 

 [b] <trim prefix="WHERE" prefixOverrides="AND|OR suffixOverrides="AND|OR""> [/b] 

 <if test="studentName !=null "> 

 ST.STUDENT_NAME LIKE CONCAT(CONCAT('%', #{studentName, jdbcType=VARCHAR}),'%') 

 </if> 

 <if test="studentSex != null and studentSex != '' "> 

 AND ST.STUDENT_SEX = #{studentSex, jdbcType=INTEGER} 

 </if> 

 <if test="studentBirthday != null "> 

 AND ST.STUDENT_BIRTHDAY = #{studentBirthday, jdbcType=DATE} 

 </if> 

 <if test="classId != null and classId!= '' "> 

 AND ST.CLASS_ID = #{classId, jdbcType=VARCHAR} 

 </if> 

 <if test="classEntity != null and classEntity.classId !=null and classEntity.classId !=' ' "> 

 AND ST.CLASS_ID = #{classEntity.classId, jdbcType=VARCHAR} 

 </if> 

 <if test="placeId != null and placeId != '' "> 

 AND ST.PLACE_ID = #{placeId, jdbcType=VARCHAR} 

 </if> 

 <if test="placeEntity != null and placeEntity.placeId != null and placeEntity.placeId != '' "> 

 AND ST.PLACE_ID = #{placeEntity.placeId, jdbcType=VARCHAR} 

 </if> 

 <if test="studentId != null and studentId != '' "> 

 AND ST.STUDENT_ID = #{studentId, jdbcType=VARCHAR} 

 </if> 

 </trim> 

 </select>

3.5.2 trim代替set


Xml代码 收藏代码

<!-- 5.2 if/trim代替set(判断参数) - 将实体类不为空的属性更新 --> 

 <update id="updateStudent_if_trim" parameterType="liming.student.manager.data.model.StudentEntity"> 

 UPDATE STUDENT_TBL 

 [b] <trim prefix="SET" suffixOverrides=","> [/b] 

 <if test="studentName != null and studentName != '' "> 

 STUDENT_TBL.STUDENT_NAME = #{studentName}, 

 </if> 

 <if test="studentSex != null and studentSex != '' "> 

 STUDENT_TBL.STUDENT_SEX = #{studentSex}, 

 </if> 

 <if test="studentBirthday != null "> 

 STUDENT_TBL.STUDENT_BIRTHDAY = #{studentBirthday}, 

 </if> 

 <if test="studentPhoto != null "> 

 STUDENT_TBL.STUDENT_PHOTO = #{studentPhoto, javaType=byte[], jdbcType=BLOB, typeHandler=org.apache.ibatis.type.BlobTypeHandler}, 

 </if> 

 <if test="classId != '' "> 

 STUDENT_TBL.CLASS_ID = #{classId}, 

 </if> 

 <if test="placeId != '' "> 

 STUDENT_TBL.PLACE_ID = #{placeId} 

 </if> 

 </trim> 

 WHERE STUDENT_TBL.STUDENT_ID = #{studentId} 

 </update>