[Gambas-user] [Gambas Bug Tracker] Bug #1100: ODBC driver super buggy 1: rs.count return always negative and only one event in lasted

[bugtracker at ...3416...]

http://gambaswiki.org/bugtracker/edit?object=BUG.1100&from=L21haW4-

Comment #4 by zxMarce:

Actually, per practically any available documentation you can check, ODBC doesn't return a row count for SELECT statements.
I'll refer you to MSDN, for example (https://docs.microsoft.com/en-us/sql/odbc/reference/syntax/sqlrowcount-function), but you can also check IBM's docs, which say the exact same:

Quote:
  SQLRowCount Function

  Conformance
  Version Introduced: ODBC 1.0 Standards Compliance: ISO 92

  Summary
  SQLRowCount returns the number of rows affected by an UPDATE, INSERT, or DELETE statement;
  an SQL_ADD, SQL_UPDATE_BY_BOOKMARK, or SQL_DELETE_BY_BOOKMARK operation in SQLBulkOperations; 
  or an SQL_UPDATE or SQL_DELETE operation in SQLSetPos

So, unless some not-so-easy mechanism is implemented, no ODBC interface will return you a row count for SELECTs.
The problem implementing the mechanism is that not all queries return a Result, for example the USE <database> command in MSSQL.

A high level ODBC interface would have a ton of things to take into account just to check whether a row count is returnable, necessary or even factible.
Add to that difficulty the fact that ODBC is actually not a driver per-se, but a driver manager and the problem only gets worse, because not all drivers implement all calls.

In short: You must use Result.Available (boolean) to check whether there are rows or not, and Result.MoveNext to loop records when dealing with ODBC.
I did implement a kind of row count for SELECTs, but it works or not depending on the underlying database driver (the one managed by ODBC), so you cannot rely on it.

One last thing: You can use a Connection String to connect to a database, if you know how to create it with your database driver of choice. Fill the Connection.Host property with the connection string instead of flling it with the Host Name and you're set. I connected to MSSQL and MySQL just changing the Connection String.

Almost forget: Regarding PHP, Java, etc, if anyone can tell me what to look at to get the infamous row count they claim they get with ODBC SELECTs, I'll appreciate it. Maybe I can add it to Gambas' ODBC.

Regards,
zxMarce.

zxMarce changed the state of the bug to: NeedsInfo.