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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 3.6.9, “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.