Sirel — A Simple Relational Algebra for PHP

Sirel is a representation of the SQL Abstract Syntax Tree in PHP.

Sirel aims to be to PHP what Arel is for Ruby.

Install

Requirements:

• PHP 5.4
• Optional: doctrine/dbal for wider Database support

Install with Composer:

php composer.phar require 'chh/sirel:1.0.*@dev'

Then require vendor/autoload.php in your app.

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Sirel is under heavy Development and so the following shortcomings and bugs still have to be ironed out:

• Only tested with SQLite, most other DBMS implement a superset of SQLite's SQL, so may also work with MySQL though.
• No Generation of DBMS-specific SQL (will likely come as Doctrine DBAL-enabled Visitor)
• Only DML (use Doctrine DBAL if you want to run database independent DDL)

Now let's dive into a bird's eye overview of the things that work ;-).

Frequently Asked Questions

How do I protect myself from SQL injection when using Sirel?

I recommend using Prepared Statements. Make sure you mark placeholders as raw SQL with Sirel::sql().

Example using PDO:

<?php

use Sirel\Sirel;
use Sirel\Table;

$users = $u = new Table("users");
$select = $users->take(1)->where($u->id->eq(Sirel::sql(':id')));

$connSpec = "…";
$pdo = new \PDO($connSpec);

$stmt = $pdo->prepare($select->toSql());
$stmt->bindParam(':id', $_GET['id']);
$stmt->execute();

$user = $stmt->fetch();

Relations

The core of Sirel's Query Building API is the Table. The Table Object provides convenient access to attributes and Factory Methods for Queries.

You may call these methods on the Table Instance to start building a new query:

• from, project, join, where, order, group, take or skip to start building a Select Query
• insert to start building an Insert Query
• update to start building an Update Query
• and delete to start building a Delete Query

The constructor takes one argument: the Table Name.

<?php
use Sirel\Table;

$users = new Table("users");

The Table Instance can additionally be accessed like an Array to get an Instance of an Attribute. If no attribute is defined, then it returns a new instance of Sirel\Attribute\Attribute.

<?php
...
echo $users['username'];
// -> users.username

// If you don't like accessing arrays:
assert($users['username'] === $users->username);

Joins

Joins look very similar to their SQL Counterparts. Joins are started by the join operator. The Join's ON Expression is then set with the next call to on. The call to on expects one or more Expressions.

Example:

<?php
use Sirel\Table;

$profiles = new Table("profiles");

echo $profiles->join($users)->on($profiles['user_id']->eq($users['id']));
// -> SELECT * FROM profiles INNER JOIN users ON profiles.user_id = users.id

Left Joins can be created with the leftJoin operator.

Example:

<?php
use Sirel\Table;

$profiles = new Table("profiles");

echo $profiles->leftJoin($users)->on($profiles['user_id']->eq($users['id']));
// -> SELECT * FROM profiles LEFT JOIN users ON profiles.user_id = users.id

Selections

Selections are done in Sirel with the where operator. The where operator takes one or more expressions as argument, which can be created by an attribute. These expressions are then joined by the "AND" Operator.

Restrictions are created by calling the respective method on an attribute. The following restrictions are supported (which each correspond to their SQL equivalents):

• eq
• notEq
• gt
• gte
• lt
• lte
• like
• notLike
• in
• notIn

Examples:

<?php
use Sirel\Table;

$users = new Table("users");

echo $users->where($users['username']->eq("johnny"), $users['password']->eq('superSecretPass'));
// -> SELECT * FROM users WHERE users.username = 'johnny' AND users.password = 'superSecretPass'

echo $users->where($users['username']->like('a%'));
// -> SELECT * FROM users WHERE users.username LIKE 'a%'

echo $users->where($users['id']->in([3, 4, 10]));
// -> SELECT * FROM users WHERE users.id IN (3, 4, 10)

Ordering

Ordering is done with the order Operator. It receives either an Order Expression or a combination of an Attribute Name and a Direction (\Sirel\Node\Order::ASC or \Sirel\Node\Order::DESC). Additionally Attribute Instances provide asc and desc methods for creating Order Expressions.

<?php
...
echo $users->order($users['username']->asc());
// -> SELECT * FROM users ORDER BY users.username ASC

echo $users->order($users['username']->desc());
// -> SELECT * FROM users ORDER BY users.username DESC

echo $users->order($users['username'], \Sirel\Node\Order::DESC);
// -> SELECT * FROM users ORDER BY users.username DESC

Use reorder to clear all current order operations:

<?php

$select = $users->order($users->username->asc())->order($users->id->asc());

// Now let's reorder:
echo $select->reorder($users->id->desc());
// -> SELECT * FROM users ORDER BY users.id DESC;

You can reverse the existing order with ->reverseOrder():

<?php

$select = $users->order($users->username->asc());

echo $select->reverseOrder();
// -> SELECT * FROM users ORDER BY users.username DESC;

Reverse only the order of some attributes by passing a list of attributes to ->reverseOrder():

<?php

$select = $users->order($users->username->asc())->order($users->id->desc());

echo $select->reverseOrder([$users->id]);
// -> SELECT * FROM users ORDER BY users.username ASC, users.id ASC;

Limit & Offset

Limit and Offset correspond to the take and skip Operators. These take the amount of rows as their sole argument.

<?php
...
echo $users->take(5);
// -> SELECT * FROM users LIMIT 5

echo $users->skip(4);
// -> SELECT * FROM users OFFSET 4

Distinct

The 'distinct' operator is used for SELECT DISTINCT queries:

<?php
echo $users->project($users['id'])->distinct();
// -> SELECT DISTINCT id FROM users;

Chaining

The greatest benefit of using a Query Builder is the composability of queries. Therefore calls to the Manager's methods are not bound to any order and can be chained infinitely.

For Example:

<?php
...
$query = $users->project($users['id']);

$query->take(1)->where($users['username']->eq("johnny"))->where($users['password']->eq('foo'));

$query->project($users['username']);

echo $query;
// -> SELECT users.id, users.username FROM users WHERE users.username = 'johnny' AND users.password = 'foo' LIMIT 1

Insert

Get an insert query manager by calling ->insert() on the table, or constructing a new Sirel\InsertManager:

<?php

$insert = $users->insert();
// is equivalent to
$insert = new Sirel\InsertManager;
$insert->into($users);

You can set a list of column-value pairs with the ->values() method:

<?php

$insert->values([
    'username' => 'jon',
    'first_name' => 'John',
    'last_name' => 'Doe'
]);

echo $insert->toSql();
// -> INSERT INTO users (users.username, users.first_name, users.last_name) VALUES ('jon', 'John', 'Doe');

Update

Update queries can be created with the table's ->update() method. Values can be set with the ->set() method.

Update queries feature most of the methods of Select queries, which work the same as their Select counterparts:

• where
• take
• skip
• order

Note: If you create an Sirel\UpdateManager instance, you need to set the table with the ->table() method.

<?php

$update = $users->update();
$update->where($users->id->eq(1))->set('last_name' => 'Foobar');

echo $update->toSql();
// -> UPDATE users SET users.last_name = 'Foobar' WHERE users.id = '1';

You can also compile an Update query from an existing Select query with ->compileUpdate():

<?php

$select = $users->where($users->first_name->eq("James"))
    ->where($users->last_name->eq("Kirk"))
    ->take(1);

$update = $select->compileUpdate()->set(['first_name' => 'Jim']);

echo $update->toSql();
// -> UPDATE users SET users.first_name = 'Jim' WHERE users.first_name = 'James' AND users.last_name = 'Kirk' LIMIT 1;

Delete

Delete queries can be created by calling the table's ->delete() method.

Delete queries understand these operations, which work exactly the same as their Select counterparts:

• from
• where
• take
• skip
• order

<?php

$delete = $users->delete()
    ->take(1)
    ->where($users->id->eq(1));

echo $delete->toSql();
// -> DELETE FROM users WHERE users.id = '1' LIMIT 1;

You can also compile an existing Select query to a Delete query:

<?php

$select = $users->where($users->activated->eq(0))->take(10);

$delete = $select->compileDelete();

echo $delete->toSql();
// -> DELETE FROM users WHERE users.activated = '0' LIMIT 10;