3.6.9 NULL mysql_store_result() Return After mysql_query() Success (original) (raw)

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3.6.9 NULL mysql_store_result() Return After mysql_query() Success

It is possible formysql_store_result() to returnNULL following a successful call to the server using mysql_real_query() or 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 could not be read (an error occurred on the connection).
• The query returned no data (for example, it was anINSERT,UPDATE, orDELETE).

You can always check whether the statement should have produced a nonempty result by callingmysql_field_count(). Ifmysql_field_count() returns zero, the result is empty and the last query was a statement that does not return values (for example, anINSERT or aDELETE). Ifmysql_field_count() returns a nonzero value, the statement should have produced a nonempty result. See the description of themysql_field_count() function for an example.

You can test for an error by callingmysql_error() ormysql_errno().