<update id="batchUpdate" parameterType="java.util.List">
 update pat_doc_pat_info set
    sex=
    <foreach collection="list" item="item" index="index" separator=" " open="case patient_id" close="end">
        when #{item.patientId} then #{item.sex}
    </foreach>
    ,address=
    <foreach collection="list" item="item" index="index" separator=" " open="case patient_id" close="end">
        when #{item.patientId} then #{item.address}
    </foreach>
    ,birth_time=
    <foreach collection="list" item="item" index="index" separator=" " open="case patient_id" close="end">
        when #{item.patientId} then #{item.birthTime}
    </foreach>
    ,remark=
    <foreach collection="list" item="item" index="index" separator=" " open="case patient_id" close="end">
        when #{item.patientId} then #{item.remark}
    </foreach>
    ,modified_time = now()
    ,belong_hospital = 1
    where delete_flag = 1 
    and doctor_id =
    <foreach collection="list" item="item" index="index" separator=" " open="case patient_id" close="end">
      when #{item.patientId} then #{item.doctor_id}
    </foreach>
    and patient_id in
    <foreach collection="list" index="index" item="item" separator="," open="(" close=")">
        #{item.patientId}
    </foreach>
</update>

int batchUpdate(List<PICAPPatientModel> list);

@Autowired
private PatDocPatInfoMapper patDocPatInfoMapper;
@Test
public void testMapperMethod () {
 List<PICAPPatientModel> updateMappingList = new ArrayList<>();
 PICAPPatientModel model1 = new PICAPPatientModel();
 model1.setPatientId(12334);
 model1.setDoctor_id(5466927);
 model1.setSex(2);
 model1.setAddress("上海市普陀區(qū)xxxx");
 model1.setBirthTime(new Date());
 model1.setRemark("哈哈哈哈");
 
 PICAPPatientModel model2 = new PICAPPatientModel();
 model2.setPatientId(5923302);
 model2.setDoctor_id(5466927);
 model2.setSex(1);
 model2.setAddress("上海市普陀區(qū)xxxx金沙江路1008號");
 model2.setBirthTime(new Date());
 model2.setRemark("哈哈哈哈adsfsa");
 
 updateMappingList.add(model1);
 updateMappingList.add(model2);
 patDocPatInfoMapper.batchUpdate(updateMappingList);
}

public Result uuu(){
    List<MdWaterSystem> list = mdWaterSystemService.findAll();
    for (MdWaterSystem mdWaterSystem : list) {
        mdWaterSystem.setWaterName(mdWaterSystem.getWaterName()+"水系");
        mdWaterSystemService.updates(mdWaterSystem);
    }
    return ResponseMsgUtil.success(list);
}

update md_water_system set water_name = CONCAT(IFNULL(water_name,''), IFNULL('水系',''));

update md_water_system set water_name = REPLACE(water_name, '水系', '')