How to fetch deleted enteries by comparing two tables

Question

Hi
I have two tables:
1. CrawlOldXml: It contains two columns "ProductName" and "ProductImageUrl". In this table, I have inserted old records like
Product1, ProductImage1.jpg
Product2, ProductImage2.jpg
Product3, ProductImage3.jpg
2. CrawlNewXml: It contains two columns "ProductName" and "ProductImageUrl". In this table, I insert new records like
Product1, ProductImage1.jpg
Product2, ProductImage3.jpg
Product4, ProductImage4.jpg
Now as we can see that in CrawlNewXml table Product2 has an updated Image url i.e. ProductImageUrl3.jpg. And also Product3 entry is removed form the CrawlNewXml table.
I want a query which could give the resulted rows which are deleted i.e. removed from table CrawlNewXml.
For example if i run a query on CrawlNewXml and CrawlOldXml then its result should be
Product3, ProductImage3.jpg

Answer 1

Hi,
You said, by using the first query, you are getting the updated records and using the second query, you are getting the updated records + deleted records. Now, you want only the deleted records. So, your second query MINUS first query would give you deleted records?
I.e
For getting the inserted/updated records :
Select ProductName, productImageUrl
From
Select 'Table A' as TableName, A.Productname. A.ProductImageUrl From CrawlNewXml as A
Union All
Select 'Table B' as TableName, B.Productname. B.ProductImageUrl From CrawlOldXml as B
)temp
Group By ProductName, ProductImageUrl
Having count(*)=1)t
where t.tableName='Table A' Order By ProductName,ProductImageUrlFor getting the Deleted Records :
Select ProductName, productImageUrl
From
Select 'Table A' as TableName, A.Productname. A.ProductImageUrl From CrawlNewXml as A
Union All
Select 'Table B' as TableName, B.Productname. B.ProductImageUrl From CrawlOldXml as B
)temp
Group By ProductName, ProductImageUrl
Having count(*)=1)t
where t.tableName='Table B' Order By ProductName,ProductImageUrl
MINUS
Select ProductName, productImageUrl
From
Select 'Table A' as TableName, A.Productname. A.ProductImageUrl From CrawlNewXml as A
Union All
Select 'Table B' as TableName, B.Productname. B.ProductImageUrl From CrawlOldXml as B
)temp
Group By ProductName, ProductImageUrl
Having count(*)=1)t
where t.tableName='Table A' Order By ProductName,ProductImageUrl-Arun
P.S : You seem to have a table without a primary key. Tables with this kind of design would yield you to this kind of difficulties ;-). Time to refactor your database design.