如果 mysql export_set() 函数中提供的任何参数为 null，则该函数将返回 null。以下示例将演示它 -
示例mysql> select export_set(null, 'y','n',',', 4);+----------------------------------+| export_set(null, 'y','n',',', 4) |+----------------------------------+| null |+----------------------------------+1 row in set (0.00 sec)mysql> select export_set(5, null,'n',',', 4);+--------------------------------+| export_set(5, null,'n',',', 4) |+--------------------------------+| null |+--------------------------------+1 row in set (0.00 sec)mysql> select export_set(5, 'y','n',',', null);+----------------------------------+| export_set(5, 'y','n',',', null) |+----------------------------------+| null |+----------------------------------+1 row in set (0.00 sec)mysql> select export_set(5, 'y','n',null, 4);+--------------------------------+| export_set(5, 'y','n',null, 4) |+--------------------------------+| null |+--------------------------------+1 row in set (0.00 sec)
以上就是如果任何参数为 null，mysql export_set() 函数返回什么？的详细内容。