+++ String functions

* The //CONCAT// function returns a string that is a concatenation of its arguments. In the example above we map the concatenation of users firstname and lastname to a value called name

<code type="php">
$q = new Doctrine_Query();

$users = $q->select('CONCAT(u.firstname, u.lastname) name')->from('User u')->execute();

foreach($users as $user) {
    // here 'name' is not a property of $user,
    // its a mapped function value
    print $user->name;
}
</code>

* The second and third arguments of the //SUBSTRING// function denote the starting position and length of the substring to be returned. These arguments are integers. The first position of a string is denoted by 1. The //SUBSTRING// function returns a string.

<code type="php">
$q = new Doctrine_Query();

$users = $q->select('u.name')->from('User u')->where("SUBSTRING(u.name, 0, 1) = 'z'")->execute();

foreach($users as $user) {
    print $user->name;
}
</code>

* The //TRIM// function trims the specified character from a string. If the character to be trimmed is not specified, it is assumed to be space (or blank). The optional trim_character is a single-character string literal or a character-valued input parameter (i.e., char or Character)[30]. If a trim specification is not provided, BOTH is assumed. The //TRIM// function returns the trimmed string.

<code type="php">
$q = new Doctrine_Query();

$users = $q->select('u.name')->from('User u')->where("TRIM(u.name) = 'Someone'")->execute();

foreach($users as $user) {
    print $user->name;
}
</code>    

* The //LOWER// and //UPPER// functions convert a string to lower and upper case, respectively. They return a string. 

<code type="php">
$q = new Doctrine_Query();

$users = $q->select('u.name')->from('User u')->where("LOWER(u.name) = 'someone'")->execute();

foreach($users as $user) {
    print $user->name;
}
</code>  

* The //LOCATE// function returns the position of a given string within a string, starting the search at a specified position. It returns the first position at which the string was found as an integer. The first argument is the string to be located; the second argument is the string to be searched; the optional third argument is an integer that represents the string position at which the search is started (by default, the beginning of the string to be searched). The first position in a string is denoted by 1. If the string is not found, 0 is returned.
* The //LENGTH// function returns the length of the string in characters as an integer.


+++ Arithmetic functions

Availible DQL arithmetic functions:

<code>
ABS(simple_arithmetic_expression)
SQRT(simple_arithmetic_expression)
MOD(simple_arithmetic_expression, simple_arithmetic_expression)
</code>

* The //ABS// function returns the absolute value for given number. 

* The //SQRT// function returns the square root for given number. 

* The //MOD// function returns the modulus of first argument using the second argument.

+++ Datetime functions