ORACLE CASE WHEN的用法与实现

 

例如:DAT_PART表中有三个栏位(PART_NO,PART_PNO,PART_MNO),传一个PART_ID值过来,查询出三个栏位中有值的那个栏位值(前提条件是三个栏位中只会一个有值),下面sql Code可以实现此功能.

 

 SELECT (
              CASE WHEN(A.PART_NO IS NULL AND A.PART_PNO IS NULL) THEN A.PART_MNO
              WHEN(A.PART_NO IS NULL AND A.PART_MNO IS NULL) THEN A.PART_PNO
              ELSE A.PART_NO
              END
      )AS V_PART_NO
      FROM DAT_PART A WHERE A.PART_ID=209435;