mySQL - Copy rows from one database to another with auto increment ids - mysql

Question

Note: Apologies if this is a duplicate but I can't find a solution.
I have two databases (one dev and one live) which have exactly the same schema.
To make things easier to explain, assume I have a 'customer' table and a 'quote' table. Both tables have auto increment ids and the quote table has a 'customerid' column that serves as a foreign key to the customer table.
My problem is that I have some rows in my dev database that I want to copy to the live database. When I copy the customer rows I can easily get a new id, but how can i get the new id to be assigned to the 'child' quote table rows?
I know I can manually script out INSERTS to overcome the problem but is there an easier way to do this?
EDIT:
This is a simplified example, I have about 15 tables all of which form a hierarchy using auto-increments and foreign keys. There is considerably more data in the live database so the new ids will be bigger (e.g. dev.customer.id = 4, live.customer.id = 54)

Answer 1

Easiest way without changing any IDs.
Ensure that you are currently in the table where the record you want to copy is in (source db).
Run the following command:
INSERT INTO to_database.to_table
SELECT * FROM from_table WHERE some_id = 123;
No need to specify columns if there is no need to remap anything.
Hope that helps!

Answer 2

I eventually managed to do this (as per my comment) but in order to do so I had to write some code. In the end I created some dummy tables that kept track of the old id against new id so. When copying over records with FK constraints I just looked up the new id based on the old. A bit long winded but it worked.
This post is getting on a bit now so I've marked this as the answer. If anyone out there has better ideas/solutions that work I'll happily 'unmark' it as the accepted answer.
EDIT: As requested here is some pseudo-code that I hope explains how I did it.
I have the two related tables as follows:
CREATE TABLE tblCustomers (
Id int NOT NULL AUTO_INCREMENT,
Name varchar(50) DEFAULT NULL,
Address varchar(255) DEFAULT NULL,
PRIMARY KEY (Id)
)
ENGINE = MYISAM
ROW_FORMAT = fixed;
CREATE TABLE tblQuotes (
Id int NOT NULL AUTO_INCREMENT,
CustomerId int(11) DEFAULT NULL,
QuoteReference varchar(50) DEFAULT NULL,
PRIMARY KEY (Id)
)
ENGINE = MYISAM
ROW_FORMAT = fixed;
I create an extra table that I will use to track old ids against new ids
CREATE TABLE tblLookupId (
Id int NOT NULL AUTO_INCREMENT,
TableName varchar(50) DEFAULT NULL,
OldId int DEFAULT NULL,
NewId int DEFAULT NULL,
PRIMARY KEY (Id)
)
ENGINE = MYISAM
ROW_FORMAT = fixed;
The idea is that I copy the tblCustomer rows one at a time and track the ids as I go, like this:
// copy each customer row from dev to live and track each old and new id
//
foreach (customer in tblCustomers)
{
// track the old id
var oldid = customer.id; // e.g. 1
// insert the new record into the target database
INSERT newdb.tblCustomers (...) VALUES (...);
// get the new id
var newid = SELECT LAST_INSERT_ID() // e.g. 245
// insert the old id and the new id in the id lookup table
INSERT idlookup (TableName, OldId, NewId) VALUES ('tblCustomers', oldid, newid); // this maps 1->245 for tblCustomers
}
When I come to copy the table (tblQuote) with the foreign key I have to first lookup the new id based on the old.
// copy each quote row from dev to live and lookup the foreign key (customer) from the lookup table
//
foreach(quote in tblQuotes)
{
// get the old foreign key value
var oldcustomerid = quote.CustomerId; // e.g 1
// lookup the new value
var newcustomerid = SELECT newid FROM tblIdLookup WHERE TableName='tblCustomers' AND oldid=oldcustomerid; // returns 245
// insert the quote record
INSERT tblQuotes (CustomerId, ...) VALUES (newcustomerid, ...);
}
I've tried to keep this short and to the point (and language agnostic) so the technique can be seen. In my real scenario I had around 15 'cascading' tables so I had to track the new ids of every table not just tblCustomer

Answer 3

Use INSERT ... SELECT:
insert into your_table (c1, c2, ...)
select c1, c2, ...
from your_table
where c1, c2, ... are all the columns except id.