odbc_num_rows() will return the
number of rows in an ODBC result. This function will return
-1 on error. For INSERT, UPDATE and DELETE statements odbc_num_rows() returns the number of
rows affected. For a SELECT clause this
can be the number of rows available.
Note: Using odbc_num_rows() to
determine the number of rows available after a SELECT will
return -1 with many drivers.