[5.8] Fix ambiguous UPDATED_AT columns

[staudenmeir]

#13519 attempted to fix ambiguous UPDATED_AT columns in JOIN queries:

class Country extends Model {
    public function posts() {
        return $this->hasManyThrough(Post::class, User::class);
    }
}

$country->posts()->update(['foo' => 'bar']);

update `posts` inner join `users` on `users`.`id` = `posts`.`user_id`
set `foo` = bar, `updated_at` = 2018-10-10 01:56:14
where `users`.`country_id` = 1

If both tables have an updated_at column, you get an "ambiguous column name" error (on MySQL).

To fix this, the previous PR qualified the column with the table name. This didn't work because PostgreSQL and SQLite don't allow qualified columns in UPDATE queries (#13707).

#22366 updated the SQLiteGrammar to remove the table name from qualified columns when an UPDATE query is compiled. This PR applies the same behavior to the PostgresGrammar.

We can now safely qualify the column on all platforms. We have to replace Arr::add() with array_merge() because the former interprets a qualified column as a nested key. $values is the second argument so that the users can override the updated_at value (as they can now).

Fixes #13909.

[samrap]

Great work! 😁

[jimmypuckett]

@driesvints Is there anyway to get this merged into 5.7? I understand that because 5.5 is LTS it gets fixed, but it would be nice to let the current stable version get the fix too?

[mfn]

I'm afraid it's not possible, as the change to compileUpdateColumns would be a breaking change in the middle of a release cycle.

[jimmypuckett]

I'm afraid it's not possible, as the change to compileUpdateColumns would be a breaking change in the middle of a release cycle.

@mfn Thanks for the feedback. It is interesting that 5.5 was able to be patched without breaking it, but that the current stable 5.7 cannot be patched.

I appreciate you taking the time to answer.

[staudenmeir]

@jimmypuckett Are you referring to #26022? We had to revert it in #26024.