mybatis plus foreach 的用法

一： foreach 用于 select * from tablename where colname in (A,B,C……);

1：service 层：

Set<String> teacherNums = new HashSet<>();
Set<String> departments = new HashSet<>();
list.stream().forEach(s->{
    teacherNums.add(s.getTeacherNumber());
    departments.add(s.getAcademeName());
});

List<GxyTeacherDto> gxyTeacherDtos = gxyTeacherMapper.selectTeaNumberBySchool(user.getOrgJson().getSchoolId(),user.getOrgJson().getSnowFlakeId(),teacherNums);
Set<String> allTeacherNum =  gxyTeacherDtos.stream().map(GxyTeacherDto::getTeacherNumber).collect(Collectors.toSet());

2： mapper 层：

List<GxyTeacherDto> selectTeaNumberBySchool(@Param("schoolId")String schoolId,@Param("snowFlakeId")Long SnowFlakeId,@Param("list") Set<String> teaNumbers);

3：xml：

<select id="selectTeaNumberBySchool" resultType="com.zhangtao.moguding.practiceservice.dto.GxyTeacherDto" >
    SELECT * FROM gxy_teacher WHERE is_deleted = 0
    <if test="schoolId != null and schoolId != ''">
        AND school_id = #{schoolId}
    </if>
    <if test="snowFlakeId != null ">
        AND snow_flake_id = #{snowFlakeId}
    </if>
    <if test="list != null and list.size >0">
        AND teacher_number in
        <foreach item="item" index="index" collection="list"
                 open="(" separator="," close=")">
            #{item}
        </foreach>
    </if>
</select>

二： update 多条sql
mapper 层：

int updateBatchByDefault(@Param("list") List<GxyPlanTeacherStudentEntity> teacherStudentEntities,@Param("tableName")String tableName);
xml：

<update id="updateBatchByDefault" parameterType="java.util.List">
    <foreach collection="list" item="item" index="index" open="" close="" separator=";">
        update <choose><when test="tableName != null and tableName !=''">${tableName}</when><otherwise>gxy_job</otherwise></choose>
        <set>
            plan_id = #{item.planId}
        </set>
        where student_id = #{item.studentId} and plan_id = #{item.defaultPlanId} and snow_flake_id = #{item.snowFlakeId} and is_deleted=0
    </foreach>
</update>

item指 List<GxyPlanTeacherStudentEntity> 中的一个 GxyPlanTeacherStudentEntity 实例对象。

三： 多个查询sql union all：
impl层：

List<GxyJobEntity> jobEntitys = gxyJobMapper.selectJob(jobs);
mapper 层：

List<GxyJobEntity> selectJob(@Param("list") List<GxyJobEntity> jobs);
xml：

<resultMap type="com.zhangtao.moguding.practiceservice.entity.GxyJobEntity" id="GxyQuartersMap">
    <result property="jobId" column="job_id"/>
    <result property="planId" column="plan_id"/>
    <result property="companyId" column="company_id"/>
    <result property="jobName" column="job_name"/>
    <result property="jobContent" column="job_content"/>
    <result property="sector" column="sector"/>
    <result property="category" column="category"/>
    <result property="quartersIntroduce" column="quarters_introduce"/>
    <result property="startTime" column="start_time"/>
    <result property="endTime" column="end_time"/>
    <result property="isMajorRight" column="is_major_right"/>
    <result property="salary" column="salary"/>
    <result property="state" column="state"/>
    <result property="applyState" column="apply_state"/>
    <result property="applyTeacherId" column="apply_teacher_id"/>
    <result property="isAuto" column="is_auto"/>
    <result property="oldJobId" column="old_job_id"/>
</resultMap>

<select id="selectJob" resultType="com.zhangtao.moguding.practiceservice.entity.GxyJobEntity" parameterType="java.util.List">
    <foreach collection="list" item="item" index="index" open="" close=""  separator=" union all">
    select t1.*
    from  <choose><when test="item.tableName1 != null and item.tableName1 !=''">${item.tableName1}</when><otherwise>gxy_job</otherwise></choose> AS t1
            <where>
                <if test="item.studentId != null and item.studentId != ''">
                    AND t1.student_id = #{item.studentId}
                </if>
                <if test="item.planId != null and item.planId != ''">
                    AND t1.plan_id = #{item.planId}
                </if>
                <if test="item.snowFlakeId != null">
                    AND t1.snow_flake_id = #{item.snowFlakeId}
                </if>
                and t1.state=1    and t1.is_deleted=0
            </where>
        </foreach>
</select>