It seems it is common sense to say it is a god practice to free any resource when it isn´t necessary anymore.
Also, when talking about releasing the resources associated with a given result set it is a common sense to say never release a result set before it is assured to have been either commited or rolled back.
Then, the following code sequence should be the most adequate (assuming auto-commit is disabled):
(PHP 4, PHP 5)
odbc_free_result — Free resources associated with a result
Free resources associated with a result.
odbc_free_result() only needs to be called if you are worried about using too much memory while your script is running. All result memory will automatically be freed when the script is finished.
The result identifier.
If auto-commit is disabled (see odbc_autocommit()) and you call odbc_free_result() before committing, all pending transactions are rolled back.
("Note: If auto-commit is disabled (see odbc_autocommit()) and you call odbc_free_result() before committing, all pending transactions are rolled back.")
I've looked thru the code, and that note is definitely wrong, at least in my environment (Windows/SQL Server). odbc_free_result ultimately just calls SQLFreeStmt which has NO EFFECT on outstanding transactions.
In fact, it seems it must be wrong for all environments, because the SQLFreeStmt is bound to the destruction of the result resource. So unset($result) would be just as dangerous - and you're randomly and unpredictably screwed if garbage collection reaps the result set before your transaction's done.
odbc_free_result() is also the way to avoid the dreaded "Too many open cursor" error.
I use WinDev 15.0 HyperFileSQL ODBC Connector on Windows, PHP 5.2.3.
With this configuration, any result ressource obtained with odbc_exec must be freed by odbc_free_result before the next query by odbc_exec.
If the result ressource is not freed odbc_exec will return a corrupt result ressource.
Output: A table with empty cells