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ezcQuery has three main purposes:

• it provides a common API for building queries through the getQuery() method.
• it provides a common API for binding parameters to queries through bindValue() and bindParam()
• it provides internal aliasing functionality that allows you to use aliases for table and column names. The substitution is done inside of the query classes before the query itself is built.

Subclasses should provide functionality to build an actual query.

The aliases can be used to substitute the column and table names with more friendly names. E.g PersistentObject uses it to allow using property and class names instead of column and table names.

This method provides a shortcut for PDOStatement::bindParam when using prepared statements.

The parameter $param specifies the variable that you want to bind. If $placeholder is not provided bind() will automatically create a placeholder for you. An automatic placeholder will be of the name 'ezcValue1', 'ezcValue2' etc.

For more information see http://php.net/pdostatement-bindparam

Example:

1.  $value = 2;
2.  $q->eq( 'id', $q->bindParam( $value ) );
3.  $stmt = $q->prepare(); // the parameter $value is bound to the query.
4.  $value = 4;
5.  $stmt->execute(); // executed with 'id = 4'

This method provides a shortcut for PDOStatement::bindValue when using prepared statements.

The parameter $value specifies the value that you want to bind. If $placeholder is not provided bindValue() will automatically create a placeholder for you. An automatic placeholder will be of the name 'ezcValue1', 'ezcValue2' etc.

For more information see http://php.net/pdostatement-bindparam

Example:

1.  $value = 2;
2.  $q->eq( 'id', $q->bindValue( $value ) );
3.  $stmt = $q->prepare(); // the value 2 is bound to the query.
4.  $value = 4;
5.  $stmt->execute(); // executed with 'id = 2'

This method must be called if you have used the bind methods in your query and you build the method yourself using build.

If the alias does not exists in the list of aliases it is returned unchanged.

This can method handles composite identifiers separated by a dot ('.').

This method is similar to getIdentifier except that it works on an array.

The returned object is a PDOStatement for which you can find extensive documentation in the PHP manual: http://php.net/pdostatement-bindcolumn

prepare() automatically calls doBind() on the statement.

This is useful if your query can be reset and used multiple times.

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:

1.  <?php
2.  $q->setAliases( array( 'Identifier' => 'id', 'Company' => 'company' ) );
3.  $q->select( 'Company' )
4.    ->from( 'table' )
5.    ->where( $q->expr->eq( 'Identifier', 5 ) );
6.  echo $q->getQuery();
7.  ?>

This example will output SQL similar to:

1.  SELECT company FROM table WHERE id = 5

Aliasses also take effect for composite names in the form tablename.columnname as the following example shows:

1.  <?php
2.  $q->setAliases( array( 'Order' => 'orders', 'Recipient' => 'company' ) );
3.  $q->select( 'Order.Recipient' )
4.    ->from( 'Order' );
5.  echo $q->getQuery();
6.  ?>

This example will output SQL similar to:

1.  SELECT orders.company FROM orders;

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):

1.  <?php
2.  $q->setAliases( array( 'Order' => 'orders', 'Recipient' => 'orders.company' ) );
3.  $q->select( 'Recipient' )
4.    ->from( 'Order' );
5.  echo $q->getQuery();
6.  ?>

This example will output SQL similar to:

1.  SELECT orders.company FROM orders;

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:

1.  <?php
2.  $q->setAliases( array( 'Order' => 'orders', 'Recipient' => 'orders.company' ) );
3.  $q->select( 'Order.Recipient' )
4.    ->from( 'Order' );
5.  echo $q->getQuery();
6.  ?>

This example will output SQL similar to:

1.  SELECT orders.Recipient FROM orders;

This method creates new ezcQuerySubSelect object that could be used for building correct subselect inside query.

Typecasting to (string) should be used to make __toString() to be called with PHP 5.1. This will not be needed in PHP 5.2 and higher when this object is used in a string context.

Example:

1.  $q->select('*')
2.    ->from( 'table1' )
3.    ->where ( $q->expr->eq( 'name', $q->bindValue( "Beeblebrox" ) ) );
4.  echo $q, "\n";