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Editorial Team
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Asked: 2026-05-28T00:35:42+00:00

What I would like to ‘have’ is someway to export my tables including the

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What I would like to ‘have’ is someway to export my tables including the foreign keys. And whenever/whereever re-execute those create table queries.

The problem I am facing though is making sure the right preconditions exist per table.

if table B references A and A references C. Then first C must be created, then A and at last B.

But creating the right order is something that I do not know how to do (yet).

I am currently creating the queries this way: (not the complete code)

class DBManager{
    private function createSQLCreateTableDump(){
        $query = "SHOW TABLES";
        $res = $this->db->prepare($query)->fetchObjectAll();
        foreach( $res as $table){
            $this->createSQLCreateTableQuery(current(get_object_vars($table)));
        }
    }

    private function createSQLCreateTableQuery($tableName){
        $query = "SHOW CREATE TABLE {$tableName}";
        $res = $this->db->prepare($query)->fetchObjectOnce();

        return $res->{"Create Table"};
    }
}

As a reference, $this->db is a class named Database which extends PDO.
fetchObjectOnce and fetchObjectAll returns each row returned as an object. The first argument (which I am not using here) specifies the class type returned. Else stdClass is used.

current(get_object_vars($table)) is used to get the first column returned. Because the column names differ per database used. This seemed the fastest/easiest way.

The problem with this method is that some tables with constraints will be created before the constraint can be created.

the question: What would be a good solution to this problem?

Just thought of this: (which I will try to work out).
I can get the constraints themself from the informatino_schema.table_constraints and key_column_usage tables. Thus I can create a tree of dependancies. Will see how far I can come that way.

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1 Answer

  1. Editorial Team

    Right, I’ve answered my own question and provided an example:

    http://pastebin.com/5dg6B0ZF

    it is not the cleanest of my work, but it works so far.

    it creates two temporary arrays.

    One holding the references per table, the other the queries.
    I am using table names as keys for the arrays for easy searching.

    I won’t accept my own answer till somewhere tomorrow to see if someone else comes up with a better solution.

    Let me know what you think.

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