Database Abstraction Layer¶

Phalcon\Db is the component behind Phalcon\Mvc\Model that powers the model layer in the framework. It consists of an independent high-level abstraction layer for database systems completely written in C.

This component allows for a lower level database manipulation than using traditional models.

This guide is not intended to be a complete documentation of available methods and their arguments. Please visit the API for a complete reference.

Database Adapters¶

This component makes use of adapters to encapsulate specific database system details. Phalcon uses PDO to connect to databases. The following database engines are supported:

Name	Description	API
MySQL	Is the world’s most used relational database management system (RDBMS) that runs as a server providing multi-user access to a number of databases	Phalcon\Db\Adapter\Pdo\Mysql
PostgreSQL	PostgreSQL is a powerful, open source relational database system. It has more than 15 years of active development and a proven architecture that has earned it a strong reputation for reliability, data integrity, and correctness.	Phalcon\Db\Adapter\Pdo\Postgresql
SQLite	SQLite is a software library that implements a self-contained, serverless, zero-configuration, transactional SQL database engine	Phalcon\Db\Adapter\Pdo\Sqlite
Oracle	Oracle is an object-relational database management system produced and marketed by Oracle Corporation.	Phalcon\Db\Adapter\Pdo\Oracle

Implementing your own adapters¶

The Phalcon\Db\AdapterInterface interface must be implemented in order to create your own database adapters or extend the existing ones.

Database Dialects¶

Phalcon encapsulates the specific details of each database engine in dialects. Those provide common functions and SQL generator to the adapters.

Name	Description	API
MySQL	SQL specific dialect for MySQL database system	Phalcon\Db\Dialect\Mysql
PostgreSQL	SQL specific dialect for PostgreSQL database system	Phalcon\Db\Dialect\Postgresql
SQLite	SQL specific dialect for SQLite database system	Phalcon\Db\Dialect\Sqlite
Oracle	SQL specific dialect for Oracle database system	Phalcon\Db\Dialect\Oracle

Implementing your own dialects¶

The Phalcon\Db\DialectInterface interface must be implemented in order to create your own database dialects or extend the existing ones.

Connecting to Databases¶

To create a connection it’s necessary instantiate the adapter class. It only requires an array with the connection parameters. The example below shows how to create a connection passing both required and optional parameters:

<?php

// Required
$config = array(
    "host" => "127.0.0.1",
    "username" => "mike",
    "password" => "sigma",
    "dbname" => "test_db"
);

// Optional
$config["persistent"] = false;

// Create a connection
$connection = new \Phalcon\Db\Adapter\Pdo\Mysql($config);

<?php

// Required
$config = array(
    "host" => "localhost",
    "username" => "postgres",
    "password" => "secret1",
    "dbname" => "template"
);

// Optional
$config["schema"] = "public";

// Create a connection
$connection = new \Phalcon\Db\Adapter\Pdo\Postgresql($config);

<?php

// Required
$config = array(
    "dbname" => "/path/to/database.db"
);

// Create a connection
$connection = new \Phalcon\Db\Adapter\Pdo\Sqlite($config);

<?php

// Basic configuration
$config = array(
    'username' => 'scott',
    'password' => 'tiger',
    'dbname' => '192.168.10.145/orcl',
);

// Advanced configuration
$config = array(
    'dbname' => '(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=localhost)(PORT=1521)))(CONNECT_DATA=(SERVICE_NAME=xe)(FAILOVER_MODE=(TYPE=SELECT)(METHOD=BASIC)(RETRIES=20)(DELAY=5))))',
    'username' => 'scott',
    'password' => 'tiger',
    'charset' => 'AL32UTF8',
);

// Create a connection
$connection = new \Phalcon\Db\Adapter\Pdo\Oracle($config);

Setting up additional PDO options¶

You can set PDO options at connection time by passing the parameters ‘options’:

<?php

// Create a connection with PDO options
$connection = new \Phalcon\Db\Adapter\Pdo\Mysql(array(
    "host" => "localhost",
    "username" => "root",
    "password" => "sigma",
    "dbname" => "test_db",
    "options" => array(
        PDO::MYSQL_ATTR_INIT_COMMAND => "SET NAMES \'UTF8\'",
        PDO::ATTR_CASE => PDO::CASE_LOWER
    )
));

Finding Rows¶

Phalcon\Db provides several methods to query rows from tables. The specific SQL syntax of the target database engine is required in this case:

<?php

$sql = "SELECT id, name FROM robots ORDER BY name";

// Send a SQL statement to the database system
$result = $connection->query($sql);

// Print each robot name
while ($robot = $result->fetch()) {
   echo $robot["name"];
}

// Get all rows in an array
$robots = $connection->fetchAll($sql);
foreach ($robots as $robot) {
   echo $robot["name"];
}

// Get only the first row
$robot = $connection->fetchOne($sql);

By default these calls create arrays with both associative and numeric indexes. You can change this behavior by using Phalcon\Db\Result::setFetchMode(). This method receives a constant, defining which kind of index is required.

Constant	Description
Phalcon\Db::FETCH_NUM	Return an array with numeric indexes
Phalcon\Db::FETCH_ASSOC	Return an array with associative indexes
Phalcon\Db::FETCH_BOTH	Return an array with both associative and numeric indexes
Phalcon\Db::FETCH_OBJ	Return an object instead of an array

<?php

$sql = "SELECT id, name FROM robots ORDER BY name";
$result = $connection->query($sql);

$result->setFetchMode(Phalcon\Db::FETCH_NUM);
while ($robot = $result->fetch()) {
   echo $robot[0];
}

The Phalcon\Db::query() returns an instance of Phalcon\Db\Result\Pdo. These objects encapsulate all the functionality related to the returned resultset i.e. traversing, seeking specific records, count etc.

<?php

$sql = "SELECT id, name FROM robots";
$result = $connection->query($sql);

// Traverse the resultset
while ($robot = $result->fetch()) {
   echo $robot["name"];
}

// Seek to the third row
$result->seek(2);
$robot = $result->fetch();

// Count the resultset
echo $result->numRows();

Binding Parameters¶

Bound parameters is also supported in Phalcon\Db. Although there is a minimal performance impact by using bound parameters, you are encouraged to use this methodology so as to eliminate the possibility of your code being subject to SQL injection attacks. Both string and positional placeholders are supported. Binding parameters can simply be achieved as follows:

<?php

// Binding with numeric placeholders
$sql    = "SELECT * FROM robots WHERE name = ? ORDER BY name";
$result = $connection->query($sql, array("Wall-E"));

// Binding with named placeholders
$sql     = "INSERT INTO `robots`(name`, year) VALUES (:name, :year)";
$success = $connection->query($sql, array("name" => "Astro Boy", "year" => 1952));

Inserting/Updating/Deleting Rows¶

To insert, update or delete rows, you can use raw SQL or use the preset functions provided by the class:

<?php

// Inserting data with a raw SQL statement
$sql     = "INSERT INTO `robots`(`name`, `year`) VALUES ('Astro Boy', 1952)";
$success = $connection->execute($sql);

//With placeholders
$sql     = "INSERT INTO `robots`(`name`, `year`) VALUES (?, ?)";
$success = $connection->execute($sql, array('Astro Boy', 1952));

// Generating dynamically the necessary SQL
$success = $connection->insert(
   "robots",
   array("Astro Boy", 1952),
   array("name", "year")
);

// Updating data with a raw SQL statement
$sql     = "UPDATE `robots` SET `name` = 'Astro boy' WHERE `id` = 101";
$success = $connection->execute($sql);

//With placeholders
$sql     = "UPDATE `robots` SET `name` = ? WHERE `id` = ?";
$success = $connection->execute($sql, array('Astro Boy', 101));

// Generating dynamically the necessary SQL
$success = $connection->update(
   "robots",
   array("name"),
   array("New Astro Boy"),
   "id = 101"
);

// Deleting data with a raw SQL statement
$sql     = "DELETE `robots` WHERE `id` = 101";
$success = $connection->execute($sql);

//With placeholders
$sql     = "DELETE `robots` WHERE `id` = ?";
$success = $connection->execute($sql, array(101));

// Generating dynamically the necessary SQL
$success = $connection->delete("robots", "id = 101");

Transactions and Nested Transactions¶

Working with transactions is supported as it is with PDO. Perform data manipulation inside transactions often increase the performance on most database systems:

<?php

try {

    //Start a transaction
    $connection->begin();

    //Execute some SQL statements
    $connection->execute("DELETE `robots` WHERE `id` = 101");
    $connection->execute("DELETE `robots` WHERE `id` = 102");
    $connection->execute("DELETE `robots` WHERE `id` = 103");

    //Commit if everything goes well
    $connection->commit();

} catch(Exception $e) {
    //An exception has occurred rollback the transaction
    $connection->rollback();
}

In addition to standard transactions, Phalcon\Db provides built-in support for nested transactions (if the database system used supports them). When you call begin() for a second time a nested transaction is created:

<?php

try {

    //Start a transaction
    $connection->begin();

    //Execute some SQL statements
    $connection->execute("DELETE `robots` WHERE `id` = 101");

    try {

        //Start a nested transaction
        $connection->begin();

        //Execute these SQL statements into the nested transaction
        $connection->execute("DELETE `robots` WHERE `id` = 102");
        $connection->execute("DELETE `robots` WHERE `id` = 103");

        //Create a save point
        $connection->commit();

    } catch(Exception $e) {
        //An error has occurred, release the nested transaction
        $connection->rollback();
    }

    //Continue, executing more SQL statements
    $connection->execute("DELETE `robots` WHERE `id` = 104");

    //Commit if everything goes well
    $connection->commit();

} catch(Exception $e) {
    //An exception has occurred rollback the transaction
    $connection->rollback();
}

Database Events¶

Phalcon\Db is able to send events to a EventsManager if it’s present. Some events when returning boolean false could stop the active operation. The following events are supported:

Event Name	Triggered	Can stop operation?
afterConnect	After a successfully connection to a database system	No
beforeQuery	Before send a SQL statement to the database system	Yes
afterQuery	After send a SQL statement to database system	No
beforeDisconnect	Before close a temporal database connection	No
beginTransaction	Before a transaction is going to be started	No
rollbackTransaction	Before a transaction is rollbacked	No
commitTransaction	Before a transaction is committed \| No

Bind an EventsManager to a connection is simple, Phalcon\Db will trigger the events with the type “db”:

<?php

use Phalcon\Events\Manager as EventsManager,
    \Phalcon\Db\Adapter\Pdo\Mysql as Connection;

$eventsManager = new EventsManager();

//Listen all the database events
$eventsManager->attach('db', $dbListener);

$connection = new Connection(array(
    "host" => "localhost",
    "username" => "root",
    "password" => "secret",
    "dbname" => "invo"
));

//Assign the eventsManager to the db adapter instance
$connection->setEventsManager($eventsManager);

Stop SQL operations are very useful if for example you want to implement some last-resource SQL injector checker:

<?php

$eventsManager->attach('db:beforeQuery', function($event, $connection) {

    //Check for malicious words in SQL statements
    if (preg_match('/DROP|ALTER/i', $connection->getSQLStatement())) {
        // DROP/ALTER operations aren't allowed in the application,
        // this must be a SQL injection!
        return false;
    }

    //It's ok
    return true;
});

Profiling SQL Statements¶

Phalcon\Db includes a profiling component called Phalcon\Db\Profiler, that is used to analyze the performance of database operations so as to diagnose performance problems and discover bottlenecks.

Database profiling is really easy With Phalcon\Db\Profiler:

<?php

use Phalcon\Events\Manager as EventsManager,
    Phalcon\Db\Profiler as DbProfiler;

$eventsManager = new EventsManager();

$profiler = new DbProfiler();

//Listen all the database events
$eventsManager->attach('db', function($event, $connection) use ($profiler) {
    if ($event->getType() == 'beforeQuery') {
        //Start a profile with the active connection
        $profiler->startProfile($connection->getSQLStatement());
    }
    if ($event->getType() == 'afterQuery') {
        //Stop the active profile
        $profiler->stopProfile();
    }
});

//Assign the events manager to the connection
$connection->setEventsManager($eventsManager);

$sql = "SELECT buyer_name, quantity, product_name "
     . "FROM buyers "
     . "LEFT JOIN products ON buyers.pid = products.id";

// Execute a SQL statement
$connection->query($sql);

// Get the last profile in the profiler
$profile = $profiler->getLastProfile();

echo "SQL Statement: ", $profile->getSQLStatement(), "\n";
echo "Start Time: ", $profile->getInitialTime(), "\n";
echo "Final Time: ", $profile->getFinalTime(), "\n";
echo "Total Elapsed Time: ", $profile->getTotalElapsedSeconds(), "\n";

You can also create your own profile class based on Phalcon\Db\Profiler to record real time statistics of the statements sent to the database system:

<?php

use Phalcon\Events\Manager as EventsManager,
    Phalcon\Db\Profiler as Profiler,
    Phalcon\Db\Profiler\Item as Item;

class DbProfiler extends Profiler
{

    /**
     * Executed before the SQL statement will sent to the db server
     */
    public function beforeStartProfile(Item $profile)
    {
        echo $profile->getSQLStatement();
    }

    /**
     * Executed after the SQL statement was sent to the db server
     */
    public function afterEndProfile(Item $profile)
    {
        echo $profile->getTotalElapsedSeconds();
    }

}

//Create an EventsManager
$eventsManager = new EventsManager();

//Create a listener
$dbProfiler = new DbProfiler();

//Attach the listener listening for all database events
$eventsManager->attach('db', $dbProfiler);

Logging SQL Statements¶

Using high-level abstraction components such as Phalcon\Db to access a database, it is difficult to understand which statements are sent to the database system. Phalcon\Logger interacts with Phalcon\Db, providing logging capabilities on the database abstraction layer.

<?php

use Phalcon\Logger,
    Phalcon\Events\Manager as EventsManager,
    Phalcon\Logger\Adapter\File as FileLogger;

$eventsManager = new EventsManager();

$logger = new FileLogger("app/logs/db.log");

//Listen all the database events
$eventsManager->attach('db', function($event, $connection) use ($logger) {
    if ($event->getType() == 'beforeQuery') {
        $logger->log($connection->getSQLStatement(), Logger::INFO);
    }
});

//Assign the eventsManager to the db adapter instance
$connection->setEventsManager($eventsManager);

//Execute some SQL statement
$connection->insert(
    "products",
    array("Hot pepper", 3.50),
    array("name", "price")
);

As above, the file app/logs/db.log will contain something like this:

[Sun, 29 Apr 12 22:35:26 -0500][DEBUG][Resource Id #77] INSERT INTO products
(name, price) VALUES ('Hot pepper', 3.50)

Implementing your own Logger¶

You can implement your own logger class for database queries, by creating a class that implements a single method called “log”. The method needs to accept a string as the first argument. You can then pass your logging object to Phalcon\Db::setLogger(), and from then on any SQL statement executed will call that method to log the results.

Describing Tables/Views¶

Phalcon\Db also provides methods to retrieve detailed information about tables and views:

<?php

// Get tables on the test_db database
$tables = $connection->listTables("test_db");

// Is there a table 'robots' in the database?
$exists = $connection->tableExists("robots");

// Get name, data types and special features of 'robots' fields
$fields = $connection->describeColumns("robots");
foreach ($fields as $field) {
    echo "Column Type: ", $field["Type"];
}

// Get indexes on the 'robots' table
$indexes = $connection->describeIndexes("robots");
foreach ($indexes as $index) {
    print_r($index->getColumns());
}

// Get foreign keys on the 'robots' table
$references = $connection->describeReferences("robots");
foreach ($references as $reference) {
    // Print referenced columns
    print_r($reference->getReferencedColumns());
}

A table description is very similar to the MySQL describe command, it contains the following information:

Index	Description
Field	Field’s name
Type	Column Type
Key	Is the column part of the primary key or an index?
Null	Does the column allow null values?

Methods to get information about views are also implemented for every supported database system:

<?php

// Get views on the test_db database
$tables = $connection->listViews("test_db");

// Is there a view 'robots' in the database?
$exists = $connection->viewExists("robots");

Creating/Altering/Dropping Tables¶

Different database systems (MySQL, Postgresql etc.) offer the ability to create, alter or drop tables with the use of commands such as CREATE, ALTER or DROP. The SQL syntax differs based on which database system is used. Phalcon\Db offers a unified interface to alter tables, without the need to differentiate the SQL syntax based on the target storage system.

Creating Tables¶

The following example shows how to create a table:

<?php

use \Phalcon\Db\Column as Column;

$connection->createTable(
    "robots",
    null,
    array(
       "columns" => array(
            new Column("id",
                array(
                    "type"          => Column::TYPE_INTEGER,
                    "size"          => 10,
                    "notNull"       => true,
                    "autoIncrement" => true,
                )
            ),
            new Column("name",
                array(
                    "type"    => Column::TYPE_VARCHAR,
                    "size"    => 70,
                    "notNull" => true,
                )
            ),
            new Column("year",
                array(
                    "type"    => Column::TYPE_INTEGER,
                    "size"    => 11,
                    "notNull" => true,
                )
            )
        )
    )
);

Phalcon\Db::createTable() accepts an associative array describing the table. Columns are defined with the class Phalcon\Db\Column. The table below shows the options available to define a column:

Option	Description	Optional
“type”	Column type. Must be a Phalcon\Db\Column constant (see below for a list)	No
“primary”	True if the column is part of the table’s primary	Yes
“size”	Some type of columns like VARCHAR or INTEGER may have a specific size	Yes
“scale”	DECIMAL or NUMBER columns may be have a scale to specify how many decimals should be stored	Yes
“unsigned”	INTEGER columns may be signed or unsigned. This option does not apply to other types of columns	Yes
“notNull”	Column can store null values?	Yes
“autoIncrement”	With this attribute column will filled automatically with an auto-increment integer. Only one column in the table can have this attribute.	Yes
“bind”	One of the BIND_TYPE_* constants telling how the column must be binded before save it	Yes
“first”	Column must be placed at first position in the column order	Yes
“after”	Column must be placed after indicated column	Yes

Phalcon\Db supports the following database column types:

Phalcon\Db\Column::TYPE_INTEGER
Phalcon\Db\Column::TYPE_DATE
Phalcon\Db\Column::TYPE_VARCHAR
Phalcon\Db\Column::TYPE_DECIMAL
Phalcon\Db\Column::TYPE_DATETIME
Phalcon\Db\Column::TYPE_CHAR
Phalcon\Db\Column::TYPE_TEXT

The associative array passed in Phalcon\Db::createTable() can have the possible keys:

Index	Description	Optional
“columns”	An array with a set of table columns defined with Phalcon\Db\Column	No
“indexes”	An array with a set of table indexes defined with Phalcon\Db\Index	Yes
“references”	An array with a set of table references (foreign keys) defined with Phalcon\Db\Reference	Yes
“options”	An array with a set of table creation options. These options often relate to the database system in which the migration was generated.	Yes

Altering Tables¶

As your application grows, you might need to alter your database, as part of a refactoring or adding new features. Not all database systems allow to modify existing columns or add columns between two existing ones. Phalcon\Db is limited by these constraints.

<?php

use Phalcon\Db\Column as Column;

// Adding a new column
$connection->addColumn("robots", null,
    new Column("robot_type", array(
        "type"    => Column::TYPE_VARCHAR,
        "size"    => 32,
        "notNull" => true,
        "after"   => "name"
    ))
);

// Modifying an existing column
$connection->modifyColumn("robots", null, new Column("name", array(
    "type" => Column::TYPE_VARCHAR,
    "size" => 40,
    "notNull" => true,
)));

// Deleting the column "name"
$connection->deleteColumn("robots", null, "name");

Dropping Tables¶

Examples on dropping tables:

<?php

// Drop table robot from active database
$connection->dropTable("robots");

//Drop table robot from database "machines"
$connection->dropTable("robots", "machines");

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