MyBatis动态SQL标签用法

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>

时间： 2024-08-08 13:54:45

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