Feature: Subqueries in the FROM section

[iRedds]

Description
This PR makes it possible to use subqueries created using the QueryBuilder instead of the table in the FROM section.

This is where we add a subquery to an existing table.::

    $subquery = $db->table('users');
    $builder  = $db->table('jobs')->fromSubquery($subquery, 'alias');
    $query = $builder->get();

    // Produces: SELECT * FROM `jobs`, (SELECT * FROM `users`) AS alias

Use the $db->newQuery() method to make a subquery the main table.::

    $subquery = $db->table('users')->select('id, name');
    $builder  = $db->newQuery()->fromSubquery($subquery, 't');
    $query = $builder->get();

    // Produces: SELECT * FROM (SELECT `id`, `name` FROM users) AS t

---

The following is the first interface. It has been modified along the way.

A subquery can be passed either directly as a variable or as an array [BaseBuilder, 'alias'] to specify an alias.

$subquery = $db->table('users');
$db->table($subquery)->get();
// SELECT * FROM (SELECT * FROM `users`)

$subquery = $db->table('jobs')
$db->table('users)->from([$subquery, 't])->get();
// SELECT * FROM `users`, (SELECT * FROM `jobs`) AS t

Only one subquery can be passed at a time.

$db->table([$subquery1, $subquery2])
// An exception will be thrown

This solution will add flexibility to the QueryBuilder and prepare the ground for other features.

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

[MGatner]

@iRedds This looks really good - I try to stay away from the database layer so I'm calling for backup. 😅

[michalsn]

Good addition.

[kenjis]

This PR seems to be good, but the method name table() and the variable name $tableName don't make sense to me.

[iRedds]

What do you mean?

[samsonasik]

@kenjis changing parameter name is bc break per php 8.0, ref https://3v4l.org/hpqdm#v8.0.14 vs https://3v4l.org/Gtdk2#v8.0.14

The current change is ok for me

[kenjis]

Originally, I was uncomfortable with the name of this table() method. However, the table() method barely made sense since it specified a table name.
I wondered if we could change the name (add a new method) to a better name if it could specify a subquery.

If no one is uncomfortable with table(), I won't insist on it.

[iRedds]

Can you suggest your own version of the method name?
I will say right away that the names of subquery and fromSubquery are not correct. In the first case, we get not a subquery, but the main query with the inclusion of a subquery. In the second case, it is associated with the QueryBuilder.

[kenjis]

createBuilder() or newBuilder().

[iRedds]

I would agree with such method names, but I associate them with creating a new/clean instance, and now this is impossible due to the fact that the class constructor requires a table name.
For example, in Laravel, the DB::table() method takes a string, a closure, a builder in the $ table parameter. That is, in this case it does not differ from my version. Except for the array. One has to scatter a rake.
But there is also an undocumented DB::query() method that returns a clean instance of the QB.
Unfortunately, our implementation already uses the query() method for a raw request. And the inability to create a clean instance of QB is a headache.

[kenjis]

Laravel has such table() method, then it might be not so bad to use table(). Because CI4 has many similar methods with Laravel.
And how about that $db->table(null) returns a new/clean QB instance?
If QB contructor's $tableName accepts null, we can do it.

[iRedds]

Alternatively, it's interesting.
But in fact, the table() method is an alias for the from() method.
And then the construction $db->table(null)->from() looks a little strange )

[michalsn]

I'm not up to date on the release planning process, so I'm not clicking the merge button. But this PR looks ready.

[iRedds]

I want to apologize to the team, but I've reworked the implementation and request a review.
It seems to me that using an array to pass the subquery + alias is bullshit.

• The from() method no longer expects a subquery. Subqueries are now processed by the fromSubquery() method.
• The from() method optimized.
• The table() method no longer expects subqueries.*
• Added newQuery() method that creates a "clean" instance of the BaseBuilder class. (Hello crutches. There is no other way)

*I thought to add the $alias parameter to the table() method in order to correctly pass the subquery with an alias,

$db->table($subquery, 'alias');

but for this I would have to change the ConnectionInterface.

[MGatner]

You don't need to apologize for improving on your work! I won't attempt a review right now but your description sounds great. Thanks for taking the extra time.

[lonnieezell]

This looks like a great addition! I like this way of handling it, also.

Can you add a test making sure that a fromSubQuery and from calls play nicely together?

[lonnieezell]

What's with the crunch table name? This seems to be getting a build instance using crunch as the table name, not "a new instance of BaseBuilder without a table" as the docblock reads.

I'm assuming this is just to fill a fake table name need? If that's the case let's use some type of random string here instead to ensure we don't accidentally conflict with a table someone might have.

[iRedds]

All attempts to change the BaseBuilder code to create a really clean instance are just marked as "breaking changes".
I hope that someday we will remove the table name from the constructor.
But so far, as I wrote above, we have no other way to create an instance other than passing a temporary fake table name to the constructor.

[kenjis]

What I want to say is that this is a big API decision that cannot be changed later and should be carefully considered by many maintainers/contributors.

And my opinion is it seems the changed fromSubquery() style is better as CI's QB than the first Laravel-like API.

[MGatner]

I'm keeping my hands off the heavy DB stuff, but the code looks good and this PR is high quality. @kenjis to you

[MGatner]

🥳