Database expressions can be used to add unescaped SQL fragments to a Database_Query_Builder object.
For example, you can use an expression to generate a column alias:
// SELECT CONCAT(first_name, last_name) AS full_name
$query = DB::select(array(DB::expr('CONCAT(first_name, last_name)'), 'full_name')));
More examples are available on the Query Builder page
Class declared in MODPATH/database/classes/database/expression.php on line 3.
Sets the expression string.
$expression = new Database_Expression('COUNT(users.id)');
string
$value
required - Raw SQL expression stringarray
$parameters
= array(0) - Unquoted parameter valuesvoidpublic function __construct($value, $parameters = array())
{
// Set the expression string
$this->_value = $value;
$this->_parameters = $parameters;
}Return the value of the expression as a string.
echo $expression;
stringpublic function __toString()
{
return $this->value();
}Bind a variable to a parameter.
string
$param
required - Parameter key to replacebyref mixed
$var
required - Variable to use$thispublic function bind($param, & $var)
{
$this->_parameters[$param] =& $var;
return $this;
}Compile the SQL expression and return it. Replaces any parameters with their given values.
mixed
$db
= NULL - Database instance or name of instancestringpublic function compile($db = NULL)
{
if ( ! is_object($db))
{
// Get the database instance
$db = Database::instance($db);
}
$value = $this->value();
if ( ! empty($this->_parameters))
{
// Quote all of the parameter values
$params = array_map(array($db, 'quote'), $this->_parameters);
// Replace the values in the expression
$value = strtr($value, $params);
}
return $value;
}Set the value of a parameter.
string
$param
required - Parameter key to replacemixed
$value
required - Value to use$thispublic function param($param, $value)
{
$this->_parameters[$param] = $value;
return $this;
}Add multiple parameter values.
array
$params
required - List of parameter values$thispublic function parameters(array $params)
{
$this->_parameters = $params + $this->_parameters;
return $this;
}Get the expression value as a string.
$sql = $expression->value();
stringpublic function value()
{
return (string) $this->_value;
}