20.4.51 Pourquoi après un mysql_query() réussi, mysql_store_result() retourne parfois NULL?

It is possible for mysql_store_result() to return NULL following a successful call to mysql_query(). When this happens, it means one of the following conditions occurred:

• There was a malloc() failure (for example, if the result set was too large).
• The data couldn't be read (an error occurred on the connection).
• The query returned no data (e.g., it was an INSERT, UPDATE or DELETE).

You can always check whether or not the statement should have produced a non-empty result by calling mysql_field_count(). If mysql_field_count() returns zero, the result is empty and the last query was a statement that does not return values (for example, an INSERT or a DELETE). If mysql_field_count() returns a non-zero value, the statement should have produced a non-empty result. See the description of the mysql_field_count() function for an example.

You can test for an error by calling mysql_error() or mysql_errno().