/**
* Sets the aliases $aliases for this object.
*
* The aliases should be in the form array( "aliasName" => "databaseName" )
* Each alias defines a relation between a user-defined name and a name
* in the database. This is supported for table names as column names.
*
* The aliases can be used to substitute the column and table names with more
* friendly names. The substitution is done when the query is built, not using
* AS statements in the database itself.
*
* Example of a select query with aliases:
* <code>
* <?php
* $q->setAliases( array( 'Identifier' => 'id', 'Company' => 'company' ) );
* $q->select( 'Company' )
* ->from( 'table' )
* ->where( $q->expr->eq( 'Identifier', 5 ) );
* echo $q->getQuery();
* ?>
* </code>
*
* This example will output SQL similar to:
* <code>
* SELECT company FROM table WHERE id = 5
* </code>
*
* Aliasses also take effect for composite names in the form
* tablename.columnname as the following example shows:
* <code>
* <?php
* $q->setAliases( array( 'Order' => 'orders', 'Recipient' => 'company' ) );
* $q->select( 'Order.Recipient' )
* ->from( 'Order' );
* echo $q->getQuery();
* ?>
* </code>
*
* This example will output SQL similar to:
* <code>
* SELECT orders.company FROM orders;
* </code>
*
* It is even possible to have an alias point to a table name/column name
* combination. This will only work for alias names without a . (dot):
* <code>
* <?php
* $q->setAliases( array( 'Order' => 'orders', 'Recipient' => 'orders.company' ) );
* $q->select( 'Recipient' )
* ->from( 'Order' );
* echo $q->getQuery();
* ?>
* </code>
*
* This example will output SQL similar to:
* <code>
* SELECT orders.company FROM orders;
* </code>
*
* In the following example, the Recipient alias will not be used, as it is
* points to a fully qualified name - the Order alias however is used:
* <code>
* <?php
* $q->setAliases( array( 'Order' => 'orders', 'Recipient' => 'orders.company' ) );
* $q->select( 'Order.Recipient' )
* ->from( 'Order' );
* echo $q->getQuery();
* ?>
* </code>
*
* This example will output SQL similar to:
* <code>
* SELECT orders.Recipient FROM orders;
* </code>
*
* @param array(string=>string) $aliases
* @return void
*/
public function setAliases(array $aliases)
{
$this->aliases = $aliases;
$this->expr->setAliases($aliases);
}
/**
* Constructs an empty ezcQueryExpression
*
* @param PDO $db
*/
public function __construct(PDO $db)
{
parent::__construct($db);
}
/**
* Constructs an pgsql expression object using the db $db.
*
* @param PDO $db
*/
public function __construct(PDO $db)
{
parent::__construct($db);
$version = $db->getAttribute(PDO::ATTR_SERVER_VERSION);
$this->version = substr($version, 0, 1);
}