UPDATE 用法总结

①

update 表a set (a.字段1,a. = (select b.字段1 from 表b where a.字段2=b.字段2) where exists(select 1 from 表b where a.字段2=b.字段2)。

②

    MERGE INTO TABLE1 A  USING
                    (SELECT CODE,NAME

                    FROM TABLE2)  B
                    ON (A.CODE= B.CODE)
                    WHEN MATCHED THEN 
                       UPDATE SET UPDATE_DT = SYSDATE
                    WHEN NOT MATCHED  THEN 
                    INSERT
                             (CODE,

                              NAME)
                     VALUES (

                               '001',

                               B.NAME

                      )

③将没有关系的表的数据放到一行中输出

SELECT A.CODE,B.COL3,C.COL1
FROM
    (SELECT * FROM TABLE1  ) A,
    (SELECT * FROM TABLE2  ) B,
    (SELECT *  from
       (SELECT t.* ,row_number()over(partition by CODE order by COL1 desc)rn FROM TABLE3 t WHERE COL6 = 1)
      WHERE rn=1 ) C,
WHERE
    A.CODE = B.CODE(+) AND
    A.EMP_CODE = C.EMP_CODE(+)

④

UPDATE  A
SET DATE=sysdate
WHERE LINK_TAISHOGAI_FG = '0'
AND (A.ID1,A.ID2,A.ID3) NOT IN
(SELECT  B.ID1,B.ID2,B.ID3 
 FROM   B
 WHERE  A.ID1= B.ID1
 AND    A.ID2 = B.ID2
 AND   A.ID3 = B.ID3 
AND    B.ID4 IN ('A','B','C'
)