SQLite - reverse string function

I solved my problem storing word reverses which I obtained via this PHP script:

class MyDB extends SQLite3
{
        function __construct()
        {
                $dbFile = __DIR__ . '/Dictionary.sqlite';
                $this->open($dbFile);
        }            
}

$db = new MyDB();

$db->createFunction('rev', 'strrev', 1);
$db->exec('UPDATE dict_en SET word_rev = rev(word)');

echo "done";

Using a common table expression it is possible to reverse a string in SQLite.

WITH reverse(i, c) AS (
    values(-1, '')
    UNION ALL SELECT i-1, substr('dlrow olleh', i, 1) AS r FROM reverse
    WHERE r!=''
) SELECT group_concat(c, '') AS reversed FROM reverse;

Returns hello world.

There is no builtin function for that. You can add custom function, like in this example in Python:

import sqlite3
conn = sqlite3.connect("")

conn.create_function("strrev", 1, lambda s: s[::-1])

cur = conn.cursor()
cur.execute(r''' SELECT strrev('hello, world') ''')
print(cur.fetchone()[0]) #dlrow ,olleh