How do I use regex in a SQLite query?

Question

I\'d like to use a regular expression in sqlite, but I don\'t know how.

My table has got a column with strings like this: \"3,12,13,14,19,28,32\" Now if I type \"whe

Answer 1

A SQLite UDF in PHP/PDO for the REGEXP keyword that mimics the behavior in MySQL:

$pdo->sqliteCreateFunction('regexp',
    function ($pattern, $data, $delimiter = '~', $modifiers = 'isuS')
    {
        if (isset($pattern, $data) === true)
        {
            return (preg_match(sprintf('%1$s%2$s%1$s%3$s', $delimiter, $pattern, $modifiers), $data) > 0);
        }

        return null;
    }
);

The u modifier is not implemented in MySQL, but I find it useful to have it by default. Examples:

SELECT * FROM "table" WHERE "name" REGEXP 'sql(ite)*';
SELECT * FROM "table" WHERE regexp('sql(ite)*', "name", '#', 's');

If either $data or $pattern is NULL, the result is NULL - just like in MySQL.

Answer 2

If you are using php you can add any function to your sql statement by using: SQLite3::createFunction. In PDO you can use PDO::sqliteCreateFunction and implement the preg_match function within your statement:

See how its done by Havalite (RegExp in SqLite using Php)

Answer 3

UPDATE TableName
 SET YourField = ''
WHERE YourField REGEXP 'YOUR REGEX'

And :

SELECT * from TableName
 WHERE YourField REGEXP 'YOUR REGEX'

Answer 4

With python, assuming con is the connection to SQLite, you can define the required UDF by writing:

con.create_function('regexp', 2, lambda x, y: 1 if re.search(x,y) else 0)

Here is a more complete example:

import re
import sqlite3

with sqlite3.connect(":memory:") as con:
    con.create_function('regexp', 2, lambda x, y: 1 if re.search(x,y) else 0)
    cursor = con.cursor()
    # ...
    cursor.execute("SELECT * from person WHERE surname REGEXP '^A' ")

Answer 5

SQLite3 supports the REGEXP operator:

WHERE x REGEXP <regex>

http://www.sqlite.org/lang_expr.html#regexp

Answer 6

for rails

            db = ActiveRecord::Base.connection.raw_connection
            db.create_function('regexp', 2) do |func, pattern, expression|
              func.result = expression.to_s.match(Regexp.new(pattern.to_s, Regexp::IGNORECASE)) ? 1 : 0
            end