SQL Server : compare two tables with UNION and Select * plus additional label column - sql

Question

I've been playing around with the sample on Jeff' Server blog to compare two tables to find the differences.
In my case the tables are a backup and the current data. I can get what I want with this SQL statement (simplified by removing most of the columns). I can then see the rows from each table that don't have an exact match and I can see from which table they come.
SELECT
MIN(TableName) as TableName
,[strCustomer]
,[strAddress1]
,[strCity]
,[strPostalCode]
FROM
(SELECT
'Old' as TableName
,[JAS001].[dbo].[AR_CustomerAddresses].[strCustomer]
,[JAS001].[dbo].[AR_CustomerAddresses].[strAddress1]
,[JAS001].[dbo].[AR_CustomerAddresses].[strCity]
,[JAS001].[dbo].[AR_CustomerAddresses].[strPostalCode]
FROM
[JAS001].[dbo].[AR_CustomerAddresses]
UNION ALL
SELECT
'New' as TableName
,[JAS001new].[dbo].[AR_CustomerAddresses].[strCustomer]
,[JAS001new].[dbo].[AR_CustomerAddresses].[strAddress1]
,[JAS001new].[dbo].[AR_CustomerAddresses].[strCity]
,[JAS001new].[dbo].[AR_CustomerAddresses].[strPostalCode]
FROM
[JAS001new].[dbo].[AR_CustomerAddresses]) tmp
GROUP BY
[strCustomer]
,[strAddress1]
,[strCity]
,[strPostalCode]
HAVING
COUNT(*) = 1
This Stack Overflow Answer gives me a much cleaner SQL query but does not tell me from which table the rows come.
SELECT * FROM [JAS001new].[dbo].[AR_CustomerAddresses]
UNION
SELECT * FROM [JAS001].[dbo].[AR_CustomerAddresses]
EXCEPT
SELECT * FROM [JAS001new].[dbo].[AR_CustomerAddresses]
INTERSECT
SELECT * FROM [JAS001].[dbo].[AR_CustomerAddresses]
I could use the first version but I have many tables that I need to compare and I think that there has to be an easy way to add the source table column to the second query. I've tried several things and googled to no avail. I suspect that maybe I'm just not searching for the correct thing since I'm sure it's been answered before.
Maybe I'm going down the wrong trail and there is a better way to compare the databases?

Answer 1

Could you use the following setup to accomplish your goal?
SELECT 'New not in Old' Descriptor, *
FROM
(
SELECT * FROM [JAS001new].[dbo].[AR_CustomerAddresses]
EXCEPT
SELECT * FROM [JAS001].[dbo].[AR_CustomerAddresses]
) a
UNION
SELECT 'Old not in New' Descriptor, *
FROM
(
SELECT * FROM [JAS001].[dbo].[AR_CustomerAddresses]
EXCEPT
SELECT * FROM [JAS001new].[dbo].[AR_CustomerAddresses]
) b

Answer 2

You can't add the table name there because union, except, and intersection all compare all columns. This means you can't differentiate between them by adding the table name to the query. A group by gives you control over what columns are considered in finding duplicates so you can exclude the table name.
To help you with the large number of tables you need to compare you could write a sql query off the metadata tables that hold table names and columns and generate the sql commands dynamically off those values.

Answer 3

Derive one column using table names like below
SELECT MIN(TableName) as TableName
,[strCustomer]
,[strAddress1]
,[strCity]
,[strPostalCode]
,table_name_came
FROM
(SELECT 'Old' as TableName
,[JAS001].[dbo].[AR_CustomerAddresses].[strCustomer]
,[JAS001].[dbo].[AR_CustomerAddresses].[strAddress1]
,[JAS001].[dbo].[AR_CustomerAddresses].[strCity]
,[JAS001].[dbo].[AR_CustomerAddresses].[strPostalCode]
,'[JAS001].[dbo].[AR_CustomerAddresses]' as table_name_came
FROM [JAS001].[dbo].[AR_CustomerAddresses]
UNION ALL
SELECT 'New' as TableName
,[JAS001new].[dbo].[AR_CustomerAddresses].[strCustomer]
,[JAS001new].[dbo].[AR_CustomerAddresses].[strAddress1]
,[JAS001new].[dbo].[AR_CustomerAddresses].[strCity]
,[JAS001new].[dbo].[AR_CustomerAddresses].[strPostalCode]
,'[JAS001new].[dbo].[AR_CustomerAddresses]' as table_name_came
FROM [JAS001new].[dbo].[AR_CustomerAddresses]
) tmp
GROUP BY [strCustomer]
,[strAddress1]
,[strCity]
,[strPostalCode]
,table_name_came
HAVING COUNT(*) = 1