select SUM(price_ghpj*num_ghpj) as 总费用 from qdoquery_ghpj where 条件
编程实现: with qdoquery_ghpj do begin first; nSum:=0; for i:=1 to recordcount do begin nSum:=nSum + fieldbyname('price_ghpj*num_ghpj').value*fieldbyname('price_ghpj*num_ghpj').value; end; end;SQL: select sum(price_ghpj*num_ghpj) from yourtable
在你的dbgrid_ghpj连接的Dataset如ADOTable1里增加一个计算字段nn,然后增加如下代码: procedure TForm1.ADOTable1CalcFields(DataSet: TDataSet); begin if ((单价<>null) and (数量<>null)) then ADOTable1.FieldByName('nn').value:=单价*数量; end;
from qdoquery_ghpj
where 条件
with qdoquery_ghpj do
begin
first;
nSum:=0;
for i:=1 to recordcount do
begin
nSum:=nSum + fieldbyname('price_ghpj*num_ghpj').value*fieldbyname('price_ghpj*num_ghpj').value;
end;
end;SQL:
select sum(price_ghpj*num_ghpj) from yourtable
内存 250 4
我的dbgrid_ghpj是可以修改的,我append后就手动输入名称,单价之类的,也就是此时数据没有在数据库,只是在dbgrid中,怎么计算
也就是我每输入完一行就自动计算
procedure TForm1.ADOTable1CalcFields(DataSet: TDataSet);
begin
if ((单价<>null) and (数量<>null)) then
ADOTable1.FieldByName('nn').value:=单价*数量;
end;