用ADOTABLE异步获取数据时,想得到打开表用的时间,每次都报错:不能将NULL转化成STRING,用其他方式能解决吗?
var
c1:int64;
t1,t2:int64;
r1:double;procedure TForm1.Button1Click(Sender: TObject);
begin
QueryPerformanceFrequency(c1);
QueryPerformanceCounter(t1);
adotable1.Open;
end;
procedure TForm1.ADOTable1AfterOpen(DataSet: TDataSet);
begin
QueryPerformanceCounter(t2);//获取结束计数值
r1:=(t2-t1)/c1;//取得计时时间,单位秒(s)
// r1:=(t2-t1)/c1*1000;//取得计时时间,单位毫秒(ms)
// r1:=(t2-t1)/c1*1000000;//取得计时时间,单位微秒
form1.Caption:=floattostr(r1)+'秒';
end;
var
c1:int64;
t1,t2:int64;
r1:double;procedure TForm1.Button1Click(Sender: TObject);
begin
QueryPerformanceFrequency(c1);
QueryPerformanceCounter(t1);
adotable1.Open;
end;
procedure TForm1.ADOTable1AfterOpen(DataSet: TDataSet);
begin
QueryPerformanceCounter(t2);//获取结束计数值
r1:=(t2-t1)/c1;//取得计时时间,单位秒(s)
// r1:=(t2-t1)/c1*1000;//取得计时时间,单位毫秒(ms)
// r1:=(t2-t1)/c1*1000000;//取得计时时间,单位微秒
form1.Caption:=floattostr(r1)+'秒';
end;
解决方案 »
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