why PHP casting MySQL BIT(1) value b'0' to boolean 'true' -

i have table in mysql structure followed:

+-------+------------------+------+-----+---------+----------------+ | field | type             | null | key | default |          | +-------+------------------+------+-----+---------+----------------+ | id    | int(10) unsigned | no   | pri | null    | auto_increment | | name  | varchar(32)      | yes  |     | null    |                | | bit   | bit(1)           | no   |     | b'0'    |                | +-------+------------------+------+-----+---------+----------------+ 

i insert record followed:

+----+-------------+-----+ | id | name        | bit | +----+-------------+-----+ |  1 | john        |     | +----+-------------+-----+ 

then use php script select , script followed:

    $pdo = new pdo("mysql:host=127.0.0.1;port=3306;dbname=test", "username","password");      $sql = "select * `for_test` `name` = :name";     $stmt = $pdo->prepare($sql);     $stmt->execute([':name' => 'john']);     while($row = $stmt->fetch(pdo::fetch_assoc)) {          var_dump((boolean)$row['bit']);     } 

i expect output should

bool(false) 

however, output

bool(true) 

why bit 0 casting 'true'?