Question

I have two mysql databases that have almost the same structure and representing the data of the same web app but one of them represents the current version and second one was made long time ago.

How can I create the database with both dumps inside but with old_ prefix for tables from the first and new_ prefix for tables from the second database?

Is there any mysqldump options to setup the prefix or other solution?

Answer 1

1. Restore both the databases as it is.
2. Use the following stored procedure to move all the tables from one DB to another DB after adding the prefix.
3. After moving delete the source database.

This stored procedure gets the table list from MySQL’s inmemory tables in information_schema and automatically moves to another DB using the RENAME command.

DELIMITER $$

USE `db`$$

DROP PROCEDURE IF EXISTS `renameDbTables`$$

CREATE DEFINER=`db`@`%` PROCEDURE `renameDbTables`(
    IN from_db VARCHAR(20),
    IN to_db VARCHAR(30),
    IN to_name_prefix VARCHAR(20)
)
BEGIN
/*
call db.renameDbTables('db1','db2','db_'); 
db1.xxx will be renamed to db2.db_xxx
*/
    DECLARE from_state_table VARCHAR(20) DEFAULT '';
    DECLARE done INT DEFAULT 0;
    DECLARE b VARCHAR(255) DEFAULT '';
    DECLARE cur1 CURSOR FOR SELECT TABLE_NAME FROM information_schema.TABLES 
        WHERE TABLE_SCHEMA=from_db;
    DECLARE CONTINUE HANDLER FOR SQLSTATE '02000' SET done = 1;

    OPEN cur1;

    REPEAT
        FETCH cur1 INTO from_state_table;
        IF NOT done THEN
--          select from_state_table;
            SET @QUERY = '';
            SET @QUERY = CONCAT(@QUERY,'RENAME TABLE ',from_db,'.', from_state_table,' TO ',to_db,'.', to_name_prefix, from_state_table,';');
--          SELECT @query;
            PREPARE s FROM @QUERY;
            EXECUTE s;
            DEALLOCATE PREPARE s;
        END IF;
    UNTIL done END REPEAT;
    CLOSE cur1;
    END$$

DELIMITER ;