无法添加或更新子行：外键约束失败

Question

SQLSTATE[23000]: Integrity constraint violation: 1452

Cannot add or update a child row: a foreign key constraint fails

( whnkepbk_Hland . interests , CONSTRAINT interests_ibfk_3 FOREIGN KEY ( scale_id ) REFERENCES scales_reference ( scale_id ))

I know that the problem is because I have to set value to scale_id to add this data line.

And I do it :

    $requete = "INSERT INTO interests (onetsoc_code,element_id,scale_id,data_value) VALUES (:onetsoc_code,:element_id,:scale_id,:data_value)"; 
...           
$InsertMetier->bindParam(':scale_id', $scale);
            var_dump($scale);
            var_dump($InsertMetier);
            $InsertMetier->execute();

Here the content of the var_dump :

</pre>Ol<pre class='xdebug-var-dump' dir='ltr'><small>string</small> <font color='#cc0000'>'Ol'</font> 

'INSERT INTO interests (onetsoc_code,element_id,scale_id,data_value) VALUES (:onetsoc_code,:element_id,:scale_id,:data_value)'

My scale variable do have a value according to the var_dump and my query sounds legitimate.

Here a screenshot of my database (interest) :

scales_reference :

Structure of interest :

Structure of scale_reference :

If someone has any idea what I have done wrong.

Answer 1

MySQL error Integrity constraint violation: 1452 from MySQL manual :

For storage engines supporting foreign keys, MySQL rejects any INSERT or UPDATE operation that attempts to create a foreign key value in a child table if there is no a matching candidate key value in the parent table.

That means you are either:

1. Inserting into your interest table with scale_id value, which doesn't exist in the parent table ( scale_reference ).
2. Having error in your query and inserting empty scale_id - from the code snippet it is not clear how you are replacing all placeholders ( :xx ) with actual values from PHP variables and we don't see the actual query as it is sent to the MySQL server.

You can try to run the desired query directly on MySQL without PHP. If it works, then you have issue in your PHP code.

Answer 2

Ol和OI之间有什么区别，您甚至无法在stackoverflow上看到它，“ oi”和“ ol”怎么样，是的，有很大的不同，我没有放置“ OI”，但我放置了OL，所以那是问题。