Improve BaseConnection::getForeignKeyData() and Forge::addForeignKey()

[sclubricants]

1. BaseConnection::getForeignKeyData()
   • Improves the method for retrieving foreign keys.
   • It aligns all DBMS to use the same naming convention.
   • It adds some more information such as delete, update, and match rules.
   • The returned dataset uses a new structure which uses one row per foreign key with an array of fields - useful for composite foreign keys.
2. Forge::addForeignKey()
   • Adds a name parameter to manual set foreign key names.
   • See [Forge] Setting key name manually for keys (unique, foreign, etc.) #5075
   • Supersedes feat: [Forge] set foreign key name manually #6370

This is the first part of #6430

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide

[kenjis]

The returned dataset uses a new structure which uses one row per foreign key with an array of fields

Can you add the structure in the user guide?

[kenjis]

@sclubricants Thank you for this PR. This is easy to understand!

The new PHPStan reports new errors. We've fixed. Please rebase to get rid of the errors.
See https://github.com/codeigniter4/CodeIgniter4/blob/develop/contributing/workflow.md#updating-your-branch

There are a few GitHub Action check failures. Also please check.

[sclubricants]

There are two PHPUnit / PHP 7.4 - MySQLi (pull_request) tests. Not sure why. Not sure why one of them is failing.

ErrorException: Undefined property: stdClass::$constraint_name

Connection::_foreignKeyData()

        $sql = '
                SELECT
                    tc.constraint_name,
                    ....
                    tc.table_name = ' . $this->escape($table);

        if (($query = $this->query($sql)) === false) {
            throw new DatabaseException(lang('Database.failGetForeignKeyData'));
        }

        $query   = $query->getResultObject();
        $indexes = [];

        foreach ($query as $row) {
            $indexes[$row->constraint_name]['constraint_name']       = $row->constraint_name;

The only way I can see this failing is if MySql isn't returning the fields in lower case. I had this problem with Oracle in upper case.

[kenjis]

There are two PHPUnit / PHP 7.4 - MySQLi (pull_request) tests. Not sure why. Not sure why one of them is failing.

The last one is MySQL 8.0.

[kenjis]

6bfd0be

Fix MySql _foreignKeyData() SQL upper case

Please write why you changed to uppercase in the commit message.

We can easily know that this commit changed the column names to uppercase,
but it is difficult to know why this change was needed from the commit.

[kenjis]

1b03ee7

Using a prefix causes problems when using dropForeignKey().

What's the problems?

[sclubricants]

What's the problems?

When you call dropForeignKey() the table parameter gets prefixed by table prefix. I mentioned it elsewhere here..

[sclubricants]

Please write why you changed to uppercase in the commit message.

Good question.. basically cause it worked. Its something I've never seen with MySql. MySql has always returned the same letter case as the sql is typed in my experience but for some reason the server you are running that test on returns upper case no matter what.

Perhaps there might be a configuration for this?

[kenjis]

basically cause it worked.

It seems MySQL 8 changed the behavior.

what are the changes in mysql 8 result rowset case? - Stack Overflow
https://stackoverflow.com/questions/54538448/what-are-the-changes-in-mysql-8-result-rowset-case

[kenjis]

When you call dropForeignKey() the table parameter gets prefixed by table prefix.

Oh, we can't drop any key that does not begin with the DB prefix!

CodeIgniter4/system/Database/Forge.php

Lines 466 to 470 in a8072a5

	$sql = sprintf(
	(string) $this->dropConstraintStr,
	$this->db->escapeIdentifiers($this->db->DBPrefix . $table),
	$this->db->escapeIdentifiers($this->db->DBPrefix . $foreignName)
	);

The DB prefix was added in:
fdb8538#diff-a07677ecb7c1a5d29e0d0a8e72f00b5b77b577508602ada4fb8c5c1e0c7c5916

[sclubricants]

Oh, we can't drop any key that does not begin with the DB prefix!

We definitely want to have the prefix. Someone might have a different connection on same database with duplicates of tables but with different prefixes. This way we avoid name collision.

[kenjis]

We definitely want to have the prefix. Someone might have a different connection on same database with duplicates of tables but with different prefixes. This way we avoid name collision.

Do we need the prefix for foreign key name?

[kenjis]

@sclubricants @michalsn Thank you!
This is a great improvement.

[MGatner]

@kenjis said it best! Thanks to everyone for the work on this 🥳