select数据库表时，将数据进行求和统计sum( *)或者count(*)时一定要 与 group by同用：

例：select
      a~MATNR
      a~meins
      a~BWART
      a~mblnr
      a~EBELN
      sum( a~MENGE ) as menge
      sum( a~DMBTR ) as dmbtr
  into corresponding fields of table g_t_result1
    from  mseg as a inner join mkpf as b on a~mblnr  = b~mblnr AND a~mjahr = b~mjahr
    where a~LGORT in s_LGORT and
          a~matnr in s_matnr and
          b~budat in s_budat
    group by a~MATNR             "SUM 和GROUP在SELECT中一起使用
             a~meins
             a~BWART
             a~mblnr
             a~EBELN . 
 

在一对多的inner join进行内表连接时，如果取出的数据有重复，前面加上distinct，这样可以删除重复的，
 也可以用 DELETE ADJACENT DUPLICATES FROM ”内表名“.