Quick easy way to migrate SQLite3 to MySQL?

Question

Anyone know a quick easy way to migrate a SQLite3 database to MySQL?

Answer 1

fallino correctly identified the location of the error in the script. I have the solution. The problem is the following lines:

line = re.sub(r"([^'])'t'(.)", "\1THIS_IS_TRUE\2", line)
line = line.replace('THIS_IS_TRUE', '1')
line = re.sub(r"([^'])'f'(.)", "\1THIS_IS_FALSE\2", line)
line = line.replace('THIS_IS_FALSE', '0')

The replacement pattern (2nd parameter) in the re.sub calls is a "regular" string, so instead of \1 expanding to the first regexp match, it expands to a literal 0x01. Likewise, \2 expands to 0x02. For example, a line containing: ,'t','f', would be replaced with: <0x01>10<0x02>
(First substitution changes ,'t', to <0x1>1<0x2> Second substitution changes <0x02>'f', to <0x1>0<0x1>)

The fix is to either change the replacement strings by adding an 'r' prefix, or by escaping the \1 and \2 in the existing string. Since easy manipulation of regexp strings is what raw strings are for, here's the fix using those:

line = re.sub(r"([^'])'t'(.)", r"\1THIS_IS_TRUE\2", line)
line = line.replace('THIS_IS_TRUE', '1')
line = re.sub(r"([^'])'f'(.)", r"\1THIS_IS_FALSE\2", line)
line = line.replace('THIS_IS_FALSE', '0')

Answer 2

I wrote this simple script in Python3. It can be used as an included class or standalone script invoked via a terminal shell. By default it imports all integers as int(11)and strings as varchar(300), but all that can be adjusted in the constructor or script arguments respectively.

NOTE: It requires MySQL Connector/Python 2.0.4 or higher

Here's a link to the source on GitHub if you find the code below hard to read: https://github.com/techouse/sqlite3-to-mysql/blob/master/sqlite3mysql.py

#!/usr/bin/env python3

__author__ = "Klemen Tušar"
__email__ = "[e-mail]"
__copyright__ = "GPL"
__version__ = "1.0.1"
__date__ = "2015-09-12"
__status__ = "Production"

import os.path, sqlite3, mysql.connector
from mysql.connector import errorcode


class SQLite3toMySQL:
    """
    Use this class to transfer an SQLite 3 database to MySQL.

    NOTE: Requires MySQL Connector/Python 2.0.4 or higher (https://dev.mysql.com/downloads/connector/python/)
    """
    def __init__(self, **kwargs):
        self._properties = kwargs
        self._sqlite_file = self._properties.get('sqlite_file', None)
        if not os.path.isfile(self._sqlite_file):
            print('SQLite file does not exist!')
            exit(1)
        self._mysql_user = self._properties.get('mysql_user', None)
        if self._mysql_user is None:
            print('Please provide a MySQL user!')
            exit(1)
        self._mysql_password = self._properties.get('mysql_password', None)
        if self._mysql_password is None:
            print('Please provide a MySQL password')
            exit(1)
        self._mysql_database = self._properties.get('mysql_database', 'transfer')
        self._mysql_host = self._properties.get('mysql_host', 'localhost')

        self._mysql_integer_type = self._properties.get('mysql_integer_type', 'int(11)')
        self._mysql_string_type = self._properties.get('mysql_string_type', 'varchar(300)')

        self._sqlite = sqlite3.connect(self._sqlite_file)
        self._sqlite.row_factory = sqlite3.Row
        self._sqlite_cur = self._sqlite.cursor()

        self._mysql = mysql.connector.connect(
            user=self._mysql_user,
            password=self._mysql_password,
            host=self._mysql_host
        )
        self._mysql_cur = self._mysql.cursor(prepared=True)
        try:
            self._mysql.database = self._mysql_database
        except mysql.connector.Error as err:
            if err.errno == errorcode.ER_BAD_DB_ERROR:
                self._create_database()
            else:
                print(err)
                exit(1)

    def _create_database(self):
        try:
            self._mysql_cur.execute("CREATE DATABASE IF NOT EXISTS `{}` DEFAULT CHARACTER SET 'utf8'".format(self._mysql_database))
            self._mysql_cur.close()
            self._mysql.commit()
            self._mysql.database = self._mysql_database
            self._mysql_cur = self._mysql.cursor(prepared=True)
        except mysql.connector.Error as err:
            print('_create_database failed creating databse {}: {}'.format(self._mysql_database, err))
            exit(1)

    def _create_table(self, table_name):
        primary_key = ''
        sql = 'CREATE TABLE IF NOT EXISTS `{}` ( '.format(table_name)
        self._sqlite_cur.execute('PRAGMA table_info("{}")'.format(table_name))
        for row in self._sqlite_cur.fetchall():
            column = dict(row)
            sql += ' `{name}` {type} {notnull} {auto_increment}, '.format(
                name=column['name'],
                type=self._mysql_string_type if column['type'].upper() == 'TEXT' else self._mysql_integer_type,
                notnull='NOT NULL' if column['notnull'] else 'NULL',
                auto_increment='AUTO_INCREMENT' if column['pk'] else ''
            )
            if column['pk']:
                primary_key = column['name']
        sql += ' PRIMARY KEY (`{}`) ) ENGINE = InnoDB CHARACTER SET utf8'.format(primary_key)
        try:
            self._mysql_cur.execute(sql)
            self._mysql.commit()
        except mysql.connector.Error as err:
            print('_create_table failed creating table {}: {}'.format(table_name, err))
            exit(1)

    def transfer(self):
        self._sqlite_cur.execute("SELECT name FROM sqlite_master WHERE type='table' AND name NOT LIKE 'sqlite_%'")
        for row in self._sqlite_cur.fetchall():
            table = dict(row)
            # create the table
            self._create_table(table['name'])
            # populate it
            print('Transferring table {}'.format(table['name']))
            self._sqlite_cur.execute('SELECT * FROM "{}"'.format(table['name']))
            columns = [column[0] for column in self._sqlite_cur.description]
            try:
                self._mysql_cur.executemany("INSERT IGNORE INTO `{table}` ({fields}) VALUES ({placeholders})".format(
                    table=table['name'],
                    fields=('`{}`, ' * len(columns)).rstrip(' ,').format(*columns),
                    placeholders=('%s, ' * len(columns)).rstrip(' ,')
                ), (tuple(data) for data in self._sqlite_cur.fetchall()))
                self._mysql.commit()
            except mysql.connector.Error as err:
                print('_insert_table_data failed inserting data into table {}: {}'.format(table['name'], err))
                exit(1)
        print('Done!')


def main():
    """ For use in standalone terminal form """
    import sys, argparse
    parser = argparse.ArgumentParser()
    parser.add_argument('--sqlite-file', dest='sqlite_file', default=None, help='SQLite3 db file')
    parser.add_argument('--mysql-user', dest='mysql_user', default=None, help='MySQL user')
    parser.add_argument('--mysql-password', dest='mysql_password', default=None, help='MySQL password')
    parser.add_argument('--mysql-database', dest='mysql_database', default=None, help='MySQL host')
    parser.add_argument('--mysql-host', dest='mysql_host', default='localhost', help='MySQL host')
    parser.add_argument('--mysql-integer-type', dest='mysql_integer_type', default='int(11)', help='MySQL default integer field type')
    parser.add_argument('--mysql-string-type', dest='mysql_string_type', default='varchar(300)', help='MySQL default string field type')
    args = parser.parse_args()

    if len(sys.argv) == 1:
        parser.print_help()
        exit(1)

    converter = SQLite3toMySQL(
        sqlite_file=args.sqlite_file,
        mysql_user=args.mysql_user,
        mysql_password=args.mysql_password,
        mysql_database=args.mysql_database,
        mysql_host=args.mysql_host,
        mysql_integer_type=args.mysql_integer_type,
        mysql_string_type=args.mysql_string_type
    )
    converter.transfer()

if __name__ == '__main__':
    main()