case when 对某个字段值分类讨论

SELECT SM_ID,SM_CID,SM_STATION,SM_TIME,PS_CODE,PS_NUMBER,SS_NAME,SS_CODE,
(CASE WHEN SM_TYPE=1 THEN '终点站'  WHEN SM_TYPE=2 THEN '中转站'  END)
FROM dbo.PDA_STATION_MANAGE sm
LEFT JOIN dbo.PDA_SIM ps ON sm.SM_CID=ps.PS_CID
LEFT JOIN dbo.SBD_STATION ss ON sm.SM_STATION=ss.SS_ID