SQLite - reverse string function

Question

Is there a function for reversing string in SQLite? I'm unable to find anything in the documentation.

Answer 1

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

Answer 2

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.