0

我有一个这样的 MySQL 表，其结构如下：

|       uri       |   title     |
_________________  _____________
Latest-Update      Latest Update
                   Latest Update

其中 uri 列是一个索引。我偶尔会在 mysql 表中执行注入，如果我有 1 个或多个同名 URI，则会出现 ERROR Duplicate Entry。所以我使用 PHP 进行插入，并希望date("m-d-y")在插入时将 a 附加到变量 $uri 的末尾。我的 INSERT 语句INSERT INTO table(uri ,title ) values('$uri', '$title')。我想看看是否在插入的表中，在 INSERT 发生之前，我是否可以判断该$uri值是否已经存在于uri表中，如果是，那么该变量将变为$uri = $uri."-"date("m-d-y");我如何判断？我做了一些研究并让我相信我应该使用INSERT...ON DUPLICATE KEY UPDATE？

4

2 回答 2

0

Not sure if you are interested in Triggers but you can depend on BEFORE INSERT trigger. Trigger requires to check if new uri being inserted has a dup entry and if yes, append dateStringOfYourFormat and insert.

Example: 

mysql> drop table mytable;
Query OK, 0 rows affected (0.03 sec)

mysql> create table mytable( uri varchar(128) );
Query OK, 0 rows affected (0.05 sec)

mysql> drop trigger uri_modifier;
ERROR 1360 (HY000): Trigger does not exist
mysql> delimiter //
mysql> create trigger uri_modifier before insert on mytable
    -> for each row
    -> begin
    ->  if ( select count(uri) from mytable where uri=NEW.uri ) > 0 then
    ->   set @modified_uri_string=concat(NEW.uri, '-', date_add(sysdate(), interval floor(rand()*1e6) microsecond));
    ->   set NEW.uri=@modified_uri_string;
    ->  end if;
    -> end//
Query OK, 0 rows affected (0.00 sec)

mysql>
mysql> delimiter ;
mysql>
mysql> set @my_new_uri_string = 'my_uri_string_to_search';
Query OK, 0 rows affected (0.00 sec)

mysql> set @modified_uri_string = @my_new_uri_string;
Query OK, 0 rows affected (0.00 sec)

mysql> select * from mytable;
Empty set (0.00 sec)

mysql> insert into mytable values(@my_new_uri_string);
Query OK, 1 row affected (0.03 sec)

mysql> select @my_new_uri_string, @modified_uri_string;
+-------------------------+-------------------------+
| @my_new_uri_string      | @modified_uri_string    |
+-------------------------+-------------------------+
| my_uri_string_to_search | my_uri_string_to_search |
+-------------------------+-------------------------+
1 row in set (0.00 sec)

mysql> select * from mytable;
+-------------------------+
| uri                     |
+-------------------------+
| my_uri_string_to_search |
+-------------------------+
1 row in set (0.00 sec)

mysql> insert into mytable values(@my_new_uri_string);
Query OK, 1 row affected (0.03 sec)

mysql> select @my_new_uri_string, @modified_uri_string;
+-------------------------+----------------------------------------------------+
| @my_new_uri_string      | @modified_uri_string                               |
+-------------------------+----------------------------------------------------+
| my_uri_string_to_search | my_uri_string_to_search-2012-05-03 02:21:39.983405 |
+-------------------------+----------------------------------------------------+
1 row in set (0.00 sec)

mysql> select * from mytable;
+----------------------------------------------------+
| uri                                                |
+----------------------------------------------------+
| my_uri_string_to_search                            |
| my_uri_string_to_search-2012-05-03 02:21:39.983405 |
+----------------------------------------------------+
2 rows in set (0.02 sec)

mysql> insert into mytable values(@my_new_uri_string);
Query OK, 1 row affected (0.01 sec)

mysql> select @my_new_uri_string, @modified_uri_string;
+-------------------------+----------------------------------------------------+
| @my_new_uri_string      | @modified_uri_string                               |
+-------------------------+----------------------------------------------------+
| my_uri_string_to_search | my_uri_string_to_search-2012-05-03 02:21:39.412580 |
+-------------------------+----------------------------------------------------+
1 row in set (0.00 sec)

mysql> select * from mytable;
+----------------------------------------------------+
| uri                                                |
+----------------------------------------------------+
| my_uri_string_to_search                            |
| my_uri_string_to_search-2012-05-03 02:21:39.983405 |
| my_uri_string_to_search-2012-05-03 02:21:39.412580 |
+----------------------------------------------------+
3 rows in set (0.00 sec)

mysql>
mysql>

Make sure that if uri inserted is different than what passed in, you have a handle to know what the modified value is.

于 2012-05-02T20:57:08.457 回答
0

这很可能是由于您的 uri 是主键。为此，您可能应该创建一个代理键，这将允许重复。如果这确实是你需要的。

于 2012-05-02T15:34:53.317 回答