“Integrity constraint violation: 1062 Duplicate entry” - but no duplicate rows

问题

I'm converting an app from native mysqli calls to PDO. Running into an error when attempting to insert a row into a table with a foreign key constraint.

Note: this is a simplified test case and should not be copy/pasted into a production environment.

Info PHP 5.3, MySQL 5.4

First, here are the tables:

CREATE TABLE `z_one` (
  `customer_id` int(10) unsigned NOT NULL DEFAULT '0',
  `name_last` varchar(255) DEFAULT NULL,
  `name_first` varchar(255) DEFAULT NULL,
  `dateadded` datetime DEFAULT NULL,
  PRIMARY KEY (`customer_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

INSERT INTO `z_one` VALUES (1,'Khan','Ghengis','2014-12-17 10:43:01');

CREATE TABLE `z_many` (
  `order_id` varchar(15) NOT NULL DEFAULT '',
  `customer_id` int(10) unsigned DEFAULT NULL,
  `dateadded` datetime DEFAULT NULL,
  PRIMARY KEY (`order_id`),
  KEY `order_index` (`customer_id`,`order_id`),
  CONSTRAINT `z_many_ibfk_1` FOREIGN KEY (`customer_id`) REFERENCES `z_one` (`customer_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

Or if you prefer,

mysql> describe z_one;
+-------------+------------------+------+-----+---------+-------+
| Field       | Type             | Null | Key | Default | Extra |
+-------------+------------------+------+-----+---------+-------+
| customer_id | int(10) unsigned | NO   | PRI | 0       |       |
| name_last   | varchar(255)     | YES  |     | NULL    |       |
| name_first  | varchar(255)     | YES  |     | NULL    |       |
| dateadded   | datetime         | YES  |     | NULL    |       |
+-------------+------------------+------+-----+---------+-------+
4 rows in set (0.00 sec)


mysql> describe z_many;
+-------------+------------------+------+-----+---------+-------+
| Field       | Type             | Null | Key | Default | Extra |
+-------------+------------------+------+-----+---------+-------+
| order_id    | varchar(15)      | NO   | PRI |         |       |
| customer_id | int(10) unsigned | YES  | MUL | NULL    |       |
| dateadded   | datetime         | YES  |     | NULL    |       |
+-------------+------------------+------+-----+---------+-------+
3 rows in set (0.00 sec)

Next, here is the query:

    $order_id = '22BD24';
    $customer_id = 1;

    try 
    {
        $q = "
            INSERT INTO 
                z_many 
                (
                    order_id,
                    customer_id,
                    dateadded
                )
            VALUES 
                (
                    :order_id,
                    :customer_id,
                    NOW()
                )
        ";
        $stmt = $dbx_pdo->prepare($q);
        $stmt->bindValue(':order_id', $order_id, PDO::PARAM_STR);
        $stmt->bindValue(':customer_id', $customer_id, PDO::PARAM_INT);
        $stmt->execute();

    } catch(PDOException $err) {
        // test case only.  do not echo sql errors to end users.
        echo $err->getMessage();
    }   

This results in the following PDO error:

SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry '22BD24' for key 'PRIMARY'

The same query works fine when handled by mysqli. Why is PDO rejecting the INSERT with a 'duplicate entry' message when there aren't any duplicates found?

回答1:

Since not all code is available (from php side) just in case your query is in some sort of loop the quickest (and perhaps partly) solution to this is the following:

$order_id = '22BD24';
$customer_id = 1;

try {
    $q = "INSERT INTO `z_many` (`order_id`,`customer_id`,`dateadded`)
        VALUES (:order_id,:customer_id,NOW())
        ON DUPLICATE KEY UPDATE `dateadded`=NOW()";

    $stmt = $dbx_pdo->prepare($q);
    $stmt->bindValue(':order_id', $order_id, PDO::PARAM_STR);
    $stmt->bindValue(':customer_id', $customer_id, PDO::PARAM_INT);
    $stmt->execute();

} catch(PDOException $err) {

    // test case only.  do not echo sql errors to end users.
    echo $err->getMessage();

}

回答2:

I've copied the SQL schema you provided on my mysql DB and added script code, but with PDO initialization at the start: $dbx_pdo = new PDO('mysql:host=127.0.0.1;dbname=test12;charset=utf8','root','');

.. and it worked fine, but my setup is php 5.5.9 and mysql 5.6.16

So I think your code executes twice and maybe its inside of a transaction, so you get rollback. Need to know more context

回答3:

Please REMOVE default for primary key column. Also use the construction

INSERT INTO (`field1`, `field2`, `...`) values (val1, val2, val3);

If you tell what default value is for inserts - some mysql versions can see errors when inserting. Thats why you should use auto-increment or dont use default value at all.

回答4:

Just a shot in the dark. I use PDO with ORACLE PL/SQL only with bindParam(). And have a look at the forth parameter ,15 if it is a PARAM_STR value. So try this, hope it helps.

   $stmt->bindParam(':order_id', $order_id, PDO::PARAM_STR, 15);
   $stmt->bindParam(':customer_id', $customer_id, PDO::PARAM_INT);

This 15 descibes the (bufffer-)length from order_id in your table.

来源：https://stackoverflow.com/questions/27529774/integrity-constraint-violation-1062-duplicate-entry-but-no-duplicate-rows