🚀 go-pugleaf

Thank you for your careful reply.
I found there is an hiden rule behind the ADOQuery and SQL :
1) if SQL is like : select * from aTable where condition,
ADOQuery->IsEmpty() will return
   properly true, if the table is really empty.
2) if SQL is like : select max(aField) as mx from aTable where condition,
even the table is empry indeed,
ADOQuery->IsEmpty() will return false(ie., the result is not empty) and
record number is 1.

Thank you again.
Frank



"Chemile" <chemile@qwest.net> д���ʼ�
news:4102b55f$1@newsgroups.borland.com...
> I use a different method to find out if a table is empty.  I modified some
> code from one of my programs, hopefully this will help you - as its
written
> for an msSQL database.
>
> Test the number of records returned from a query with: pQuery->RecordCount
> Test if a feild is null with:
> if(!VarIsNull(pQuery->FieldValues["Name"])){ }else{ }
> Use the second example if you just want to know the number of records in a
> table, without returning extra data.
>
> ///////////////////////////////////////////////////
>
>   AnsiString AqMask = "*", AqTable = "MyTable", AqCol = "MyFeild",
AqSearch
> = "Hello";
>   int limit = 999;
>
>   TADOQuery *pQuery = new TADOQuery(0);
>   pQuery->Connection = ADOConnection1;
>   pQuery->CursorType = ctKeyset;
>   pQuery->CacheSize = 10000;
>   pQuery->CursorLocation = clUseClient;
>   pQuery->LockType = ltReadOnly;
>
>   pQuery->Close();
>   pQuery->SQL->Clear();
>   pQuery->SQL->Add("SELECT top " + String(limit) + "  " + AqMask + " from
"
> + AqTable + " WHERE LOWER(" + AqCol + ") = LOWER('" +
ParseStream(AqSearch)
> + "')");
>   pQuery->Open();
>
>   if(pQuery->RecordCount == 0){ ShowMessage("Query Returned Zero
Results!");
> return; }
>
>   //Capture Headers//
>   AnsiString nLine = "";
>   nLine = "";
>   for(int tmp = 0; tmp < pQuery->FieldList->Count; tmp++){
>     if(nLine != "") nLine = nLine + ",";
>     nLine = nLine + "\"" + pQuery->FieldList->Strings[tmp] + "\"";
>   }
>   Memo1->Lines->Add(nLine);
>
>   for(int tmp = 0; tmp < pQuery->RecordCount; tmp++){
>     AnsiString pLine = "";
>
>     //Get Items//
>     pLine = "";
>     for(int tmp3 = 0; tmp3 < pQuery->FieldList->Count; tmp3++){
>
if(!VarIsNull(pQuery->FieldValues[pQuery->FieldList->Strings[tmp3]])){
>         if(pLine != "") pLine = pLine + ",";
>           pLine = pLine + "\"" +
> pQuery->FieldValues[pQuery->FieldList->Strings[tmp3]] + "\"";
>         }else{
>           if(pLine != "") pLine = pLine + ",";
>           pLine = pLine + "\"\"";
>         }
>       }
>       //Use Data Here, Before its Overwritten//
>       Memo1->Lines->Add(pLine);
>       pQuery->Next();
>     }
>   }
>
>
>
> ///////////////////////////////////////////////////
>
>   TADOQuery *pQuery = new TADOQuery(0);
>   pQuery->Connection = ADOConnection1;
>   pQuery->CursorType = ctKeyset;
>   pQuery->CacheSize = 10000;
>   pQuery->CursorLocation = clUseClient;
>   pQuery->LockType = ltReadOnly;
>
>   pQuery->Close();
>   pQuery->SQL->Clear();
>   pQuery->SQL->Add("SELECT count (*) from " + AqTable + " WHERE LOWER(" +
> AqCol + ")=LOWER('" + ParseStream(AqSearch) + "')");
>   pQuery->Open();
>
>   int pCount = pQuery->Fields->Fields[0]->AsInteger;
>
>   if(pCount > 0){
>     //Put your code here//
>   }
>
>