Returns the number of columns for the most recent query on the connection.

The normal use of this function is whenmysql_store_result()returnedNULL(and thus you have no result set pointer). In this case, you can callmysql_field_count()to determine whethermysql_store_result()should have produced a nonempty result. This enables the client program to take proper action without knowing whether the query was aSELECT(orSELECT-like) statement. The example shown here illustrates how this may be done.

SeeSection 3.6.8, “NULL mysql_store_result() Return After mysql_query() Success”.

An unsigned integer representing the number of columns in a result set.

None.

MYSQL_RES *result; unsigned int num_fields; unsigned int num_rows; if (mysql_query(&mysql,query_string)) { // error } else // query succeeded, process any data returned by it { result = mysql_store_result(&mysql); if (result) // there are rows { num_fields = mysql_num_fields(result); // retrieve rows, then call mysql_free_result(result) } else // mysql_store_result() returned nothing; should it have? { if(mysql_field_count(&mysql) == 0) { // query does not return data // (it was not a SELECT) num_rows = mysql_affected_rows(&mysql); } else // mysql_store_result() should have returned data { fprintf(stderr, "Error: %s\n", mysql_error(&mysql)); } } }

An alternative is to replace themysql_field_count(&mysql)call withmysql_errno(&mysql). In this case, you are checking directly for an error frommysql_store_result()rather than inferring from the value ofmysql_field_count()whether the statement was aSELECT.