asked on

successive table record count problems

I present a list of databases to the user, as they scroll through them I show among other things the record count. Each time I reset the databasename and tablename for the table and call the function TableCount as follows:

label1.Caption := IntToStr(TableCount(table1.DBHandle));

where

function TableCount(hDb: hDBIDb): longint;
{to use the function, pass in either TDatabase.handle or
TTable.DBHandle. The TDatabase or TTable must be open in both cases}
var
hCur: hDBICur;
begin
Result := 0;
Check(DbiOpenTableList(hDb,FALSE, FALSE, '*.*', hCur));
try
Check(DbiGetRecordCount(hCur, Result));
finally
Check(DbiCloseCursor(hCur));
end;
end;

The problem is that the record count does not update after the first time, it returns the same number of records everytime. Any ideas?

Thanks, Tom.

kjteng

did u set any range limit?
why don't u use the recordcount property?

boardtc

ASKER

I only do what I show. I was lead to understand that there was more overhead using recordcount. For example it's more efficient to check if both BOF and EOF are True to see if a table is empty than checking recordcount is zero. Tom.

ZifNab

is the line Check(DbiCloseCursor(hCur)) always executed after the first try?

boardtc

ASKER

Yes, every time a new database is selected I do
label1.Caption := IntToStr(TableCount(table1.DBHandle));

ZifNab

So table1.Dbhandle changes from table to table? Or not? If Table1 stays table1 it's normal you don't see any change in the record count when you just browse through the table. Record count just gives the total of records.

ronit051397

I think you should pass the table Handle and not the Table DBHandle.
In this case you will get a compilation error because DbiOpenTableList takes a DBHandle but DbiGetRecordCount takes a handle, so I don't know how you find the Handle out of the DBHandle.

boardtc

ASKER

DBHandle does change I checked that....go figure. Interesting Ronit.

rickpet

Ronit...your on the right path...

Check(DbiOpenTableList(hDb,FALSE, FALSE, '*.*', hCur));

This bde call returns the cursor to a table of all tables in the Database...in hCur
So you should always get the same value...the total number of tables

Change it to something like...

function TableCount(Value: TTable): longint;
{to use the function, pass in TTable}
var
hCur: hDBICur;
begin
Result := 0;
Check(dbiGetCursorForTable(Value.DbHandle, pchar(Value), nil, hCur));
try
Check(DbiGetRecordCount(hCur, Result));
finally
Check(DbiCloseCursor(hCur));
end;
end;

Rick

boardtc

ASKER

Rick,

Thanks for the respose. I tried your implementation, passing in ttable (tablename and databasename set, active is True) I get the error - unable to open object on the line:

Check(dbiGetCursorForTable(Value.DbHandle, pchar(Value), nil, hCur));

Any ideas? Thanks, Tom.

rickpet

Okay this works...opps on the pchar value...should be pchar(Value.TableName) not pchar(Value)

function TForm1.TableCount(Value: TTable): longint;
{to use the function, pass in TTable}
var
hCur: hDBICur;
begin
if not Value.Active then
Value.open;
Result := 0;
Check(dbiGetCursorForTable(Value.DbHandle, pchar(Value.TableName), nil, hCur));
Check(DbiGetRecordCount(hCur, Result));
(* Check(DbiCloseCursor(hCur));
Don't need to close as dbiGetCursorForTable only returns an existing cursor.
*)
end;

boardtc

ASKER

Rick,

That worked geat, I shoud have checked the BDE help myself. Thanks for the DBiCloseCursor info. Put in a dummy answer and I'll grade. Tom.

rickpet

Tom...this one's on me...

I owe you...for that last one...

Also you don't need to even use...
Check(dbiGetCursorForTable(Value.DbHandle, pchar(Value.TableName), nil, hCur));

since Table1.handle is a hDBICur.
from TBDEDataSet help
property Handle: HDBICur;

Rick

boardtc

ASKER

Rick,

Nice one. After all that it come down to:

function TableCount(tbl: TTable): longint;
{ the TTable must be open }
begin
Check(DbiGetRecordCount(tbl.Handle, Result));
end;

That's generous of you. Should I just delete?

Tom.

rickpet

Yes...

Rick

rickpet

or just set the value to 0

Rick

boardtc

ASKER

Thing is I'd like to make this available, you can't decrease the points. I have no worries giving them to you. Tom.

ASKER CERTIFIED SOLUTION

rickpet

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