怎样用merge合并A、B两张表?A表有河南省的企业股票代码，季度，B表有所有的企业股票代码，季度，企业利润

A表：
input long Stkcd str12 Stknme str10 Accper
401 "冀东水泥" "2016/03/31"
401 "冀东水泥" "2016/06/30"
401 "冀东水泥" "2016/09/30"
401 "冀东水泥" "2016/12/31"
401 "冀东水泥" "2017/03/31"
401 "冀东水泥" "2017/06/30"
401 "冀东水泥" "2017/09/30"
401 "冀东水泥" "2017/12/31"
401 "冀东水泥" "2018/03/31"
401 "冀东水泥" "2018/06/30"
end

B表：
input long Stkcd str10 Accper double Totalprofit
2 "2016/1/1"   33802617619
2 "2016/12/31" 39253611726
2 "2016/3/31"   1687268596
2 "2016/6/30"  12872446834
2 "2016/9/30"  15961171833
2 "2017/1/1"   39253611726
2 "2017/12/31" 51141952665
2 "2017/3/31"   1571531169
2 "2017/6/30"  13826911378
2 "2017/9/30"  20901592187
end