MyBatis动态SQL标签用法实例详解

时间：2020-10-08 13:26:34|栏目：JAVA代码|点击：次

1、动态SQL片段

通过SQL片段达到代码复用

 <!-- 动态条件分页查询 --> 
    <sql id="sql_count"> 
        select count(*) 
    </sql> 
    <sql id="sql_select"> 
        select * 
    </sql> 
    <sql id="sql_where"> 
        from icp 
        <dynamic prepend="where"> 
            <isNotEmpty prepend="and" property="name"> 
                name like '%$name$%' 
            </isNotEmpty> 
            <isNotEmpty prepend="and" property="path"> 
                path like '%path$%' 
            </isNotEmpty> 
            <isNotEmpty prepend="and" property="area_id"> 
                area_id = #area_id# 
            </isNotEmpty> 
            <isNotEmpty prepend="and" property="hided"> 
                hided = #hided# 
            </isNotEmpty> 
        </dynamic> 
        <dynamic prepend=""> 
            <isNotNull property="_start"> 
                <isNotNull property="_size"> 
                    limit #_start#, #_size# 
                </isNotNull> 
            </isNotNull> 
        </dynamic> 
    </sql> 
    <select id="findByParamsForCount" parameterClass="map" resultClass="int"> 
        <include refid="sql_count"/> 
        <include refid="sql_where"/> 
    </select> 
    <select id="findByParams" parameterClass="map" resultMap="icp.result_base"> 
        <include refid="sql_select"/> 
        <include refid="sql_where"/> 
    </select>

2、数字范围查询

所传参数名称是捏造所得，非数据库字段，比如_img_size_ge、_img_size_lt字段

 <isNotEmpty prepend="and" property="_img_size_ge"> 
                <![CDATA[ 
                img_size >= #_img_size_ge# 
            ]]> 
            </isNotEmpty> 
            <isNotEmpty prepend="and" property="_img_size_lt"> 
                <![CDATA[ 
                img_size < #_img_size_lt# 
            ]]> 
            </isNotEmpty>

多次使用一个参数也是允许的

    <isNotEmpty prepend="and" property="_now"> 
                <![CDATA[ 
                      execplantime >= #_now# 
                   ]]> 
            </isNotEmpty> 
            <isNotEmpty prepend="and" property="_now"> 
                <![CDATA[ 
                      closeplantime <= #_now# 
                   ]]> 
            </isNotEmpty>

3、时间范围查询

   <isNotEmpty prepend="" property="_starttime"> 
                <isNotEmpty prepend="and" property="_endtime"> 
                    <![CDATA[ 
                    createtime >= #_starttime# 
                    and createtime < #_endtime# 
                 ]]> 
                </isNotEmpty> 
            </isNotEmpty>

4、in查询

  <isNotEmpty prepend="and" property="_in_state"> 
                state in ('$_in_state$') 
            </isNotEmpty>

5、like查询

  <isNotEmpty prepend="and" property="chnameone"> 
                (chnameone like '%$chnameone$%' or spellinitial like '%$chnameone$%') 
            </isNotEmpty> 
            <isNotEmpty prepend="and" property="chnametwo"> 
                chnametwo like '%$chnametwo$%' 
            </isNotEmpty>

6、or条件

 <isEqual prepend="and" property="_exeable" compareValue="N"> 
                <![CDATA[ 
                (t.finished='11'  or t.failure=3) 
            ]]> 
            </isEqual>
 
            <isEqual prepend="and" property="_exeable" compareValue="Y"> 
                <![CDATA[ 
                t.finished in ('10','19') and t.failure<3 
            ]]> 
            </isEqual>

7、where子查询

 <isNotEmpty prepend="" property="exprogramcode"> 
                <isNotEmpty prepend="" property="isRational"> 
                    <isEqual prepend="and" property="isRational" compareValue="N"> 
                        code not in 
                        (select t.contentcode 
                        from cms_ccm_programcontent t 
                        where t.contenttype='MZNRLX_MA' 
                        and t.programcode = #exprogramcode#) 
                    </isEqual> 
                </isNotEmpty> 
            </isNotEmpty>
    <select id="findByProgramcode" parameterClass="string" resultMap="cms_ccm_material.result"> 
        select * 
        from cms_ccm_material 
        where code in 
        (select t.contentcode 
        from cms_ccm_programcontent t 
        where t.contenttype = 'MZNRLX_MA' 
        and programcode = #value#) 
        order by updatetime desc 
    </select>

9、函数的使用

  <!-- 添加 --> 
    <insert id="insert" parameterClass="RuleMaster"> 
        insert into rulemaster( 
        name, 
        createtime, 
        updatetime, 
        remark 
        ) values ( 
        #name#, 
        now(), 
        now(), 
        #remark# 
        ) 
        <selectKey keyProperty="id" resultClass="long"> 
            select LAST_INSERT_ID() 
        </selectKey> 
    </insert> 
    <!-- 更新 --> 
    <update id="update" parameterClass="RuleMaster"> 
        update rulemaster set 
        name = #name#, 
        updatetime = now(), 
        remark = #remark# 
        where id = #id# 
    </update>

10、map结果集

 <!-- 动态条件分页查询 --> 
    <sql id="sql_count"> 
        select count(a.*) 
    </sql> 
    <sql id="sql_select"> 
        select a.id        vid, 
        a.img       imgurl, 
        a.img_s     imgfile, 
        b.vfilename vfilename, 
  b.name      name, 
        c.id        sid, 
        c.url       url, 
        c.filename  filename, 
        c.status    status 
    </sql> 
    <sql id="sql_where"> 
        From secfiles c, juji b, videoinfo a 
        where 
        a.id = b. videoid 
        and b.id = c.segmentid 
        and c.status = 0 
        order by a.id asc,b.id asc,c.sortnum asc 
        <dynamic prepend=""> 
            <isNotNull property="_start"> 
                <isNotNull property="_size"> 
                    limit #_start#, #_size# 
                </isNotNull> 
            </isNotNull> 
        </dynamic> 
    </sql> 
    <!-- 返回没有下载的记录总数 --> 
    <select id="getUndownFilesForCount" parameterClass="map" resultClass="int"> 
        <include refid="sql_count"/> 
        <include refid="sql_where"/> 
    </select> 
    <!-- 返回没有下载的记录 --> 
    <select id="getUndownFiles" parameterClass="map" resultClass="java.util.HashMap"> 
        <include refid="sql_select"/> 
        <include refid="sql_where"/> 
    </select>

11、trim

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。

where例子的等效trim语句：

Xml代码

<!-- 查询学生list，like姓名，=性别 -->  
<select id="getStudentListWhere" parameterType="StudentEntity" resultMap="studentResultMap">  
  SELECT * from STUDENT_TBL ST  
  <trim prefix="WHERE" prefixOverrides="AND|OR">  
    <if test="studentName!=null and studentName!='' ">  
      ST.STUDENT_NAME LIKE CONCAT(CONCAT('%', #{studentName}),'%')  
    </if>  
    <if test="studentSex!= null and studentSex!= '' ">  
      AND ST.STUDENT_SEX = #{studentSex}  
    </if>  
  </trim>  
</select>

set例子的等效trim语句：

Xml代码

<!-- 更新学生信息 -->  
<update id="updateStudent" parameterType="StudentEntity">  
  UPDATE STUDENT_TBL  
  <trim prefix="SET" suffixOverrides=",">  
    <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="classEntity!=null and classEntity.classID!=null and classEntity.classID!='' ">  
      STUDENT_TBL.CLASS_ID = #{classEntity.classID}  
    </if>  
  </trim>  
  WHERE STUDENT_TBL.STUDENT_ID = #{studentID};  
</update>

12、choose (when, otherwise)

有时候我们并不想应用所有的条件，而只是想从多个选项中选择一个。MyBatis提供了choose 元素，按顺序判断when中的条件出否成立，如果有一个成立，则choose结束。当choose中所有when的条件都不满则时，则执行 otherwise中的sql。类似于Java 的switch 语句，choose为switch，when为case，otherwise则为default。

if是与(and)的关系，而choose是或（or）的关系。

例如下面例子，同样把所有可以限制的条件都写上，方面使用。选择条件顺序，when标签的从上到下的书写顺序：

Xml代码

<!-- 查询学生list，like姓名、或=性别、或=生日、或=班级，使用choose -->  
<select id="getStudentListChooseEntity" parameterType="StudentEntity" resultMap="studentResultMap">  
  SELECT * from STUDENT_TBL ST  
  <where>  
    <choose>  
      <when test="studentName!=null and studentName!='' ">  
          ST.STUDENT_NAME LIKE CONCAT(CONCAT('%', #{studentName}),'%')  
      </when>  
      <when test="studentSex!= null and studentSex!= '' ">  
          AND ST.STUDENT_SEX = #{studentSex}  
      </when>  
      <when test="studentBirthday!=null">  
        AND ST.STUDENT_BIRTHDAY = #{studentBirthday}  
      </when>  
      <when test="classEntity!=null and classEntity.classID !=null and classEntity.classID!='' ">  
        AND ST.CLASS_ID = #{classEntity.classID}  
      </when>  
      <otherwise>  
      </otherwise>  
    </choose>  
  </where>  
</select>

以上所述是小编给大家介绍的MyBatis动态SQL标签用法实例详解，希望对大家有所帮助，如果大家有任何疑问欢迎给我留言，小编会及时回复大家的！

上一篇：Java 批量删除html中注释内容的方法

栏目：JAVA代码

下一篇：Java异或技操作给任意的文件加密原理及使用详解

本文标题：MyBatis动态SQL标签用法实例详解

本文地址：http://www.codeinn.net/misctech/8371.html

更多JAVA代码

JAVA代码

MyBatis动态SQL标签用法实例详解

阅读排行

推荐教程