variable database name

Question

Is there any way in MySQL to put the name of the database into a variable? For example, when I have a database called \'db1\', can I do something like this:

Answer 1

If you have PHP installed you could use this script to replace the mysql variables to there actual value:

<?php

$sqlFile = 'migration.sql';
$fromDb = 'db1';
$toDb = 'db2';

echo str_replace(['@fromDb', '@toDb'], [$fromDb, $toDb], file_get_contents($sqlFile));

Answer 2

Using Chaos' 'Prepare Statement' solution I managed to create a Stored Procedure which uses a variable database name.

Works like a charm for migrating data from one database to another with a Stored Procedure. This way the code isn't pinned to a single database.

DELIMITER $$

DROP PROCEDURE IF EXISTS `SampleProcedure` $$
CREATE PROCEDURE `SampleProcedure`(IN HubDatabaseName VARCHAR(255))
BEGIN

SET @db = HubDatabaseName;
SET @q = CONCAT('

/* Import data from Hub database to local database */
INSERT INTO `table_name_in_local_database`
SELECT
  *
FROM
  ', @db ,'.`tablename`

');

PREPARE stmt FROM @q;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;

END $$
DELIMITER ;

Answer 3

With considerable effort, yes.

SET @db = 'db1';
SET @q = CONCAT('SELECT * FROM ', @db, '.mycol');
PREPARE stmt FROM @q;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;