sql || 连接符

SELECT A.FOLLOW_SURVEY_CD,A.REVICE_CD FROM 
  (SELECT B.FOLLOW_SURVEY_CD, A.SURVEY_CD||B.SURVEY_DETAIL_CD AS REVICE_CD 
       FROM SMS_SURVEY A ,SMS_SURVEY_DETAIL B 
           WHERE A.SURVEY_ID=B.SURVEY_ID AND A.DATA_STATE='0' AND B.DATA_STATE='0' AND B.FOLLOW_SURVEY_CD IS NOT NULL) A 

 WHERE A.REVICE_CD = 'surveyCd'

两个字段的值 拼接在一起