两个Update语句

1.

    EXEC SQL.
      update (select a.lifnr,b.lifnr as new_lifnr
              from   zgr_his_tmp a,
                     ekko b
              where  b.mandt=a.mandt and
                     b.ebeln=a.ebeln
             )
      set    lifnr=new_lifnr
    ENDEXEC.

 

2.

    EXEC SQL.
      UPDATE ZGR_HIS_TMP SET LIFNR = ( SELECT LIFNR
                    FROM EKKO WHERE
                    EKKO.MANDT=ZGR_HIS_TMP.MANDT AND
                    EKKO.EBELN=ZGR_HIS_TMP.EBELN )

    ENDEXEC.

 

一般来说，第一个效率能高些。

如果哪位有效率更高的语句，请留言。谢谢！