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I am trying to compare two tables, SQL Server, to verify some data. I want to return all the rows from both tables where data is either in one or the other. In essence, I want to show all the discrepancies. I need to check three pieces of data in doing so, FirstName, LastName, and Product.

I'm fairly new to SQL and it seems like a lot of the solutions I'm finding are over complicating things. I don't have to worry about NULLs.

I started by trying something like this:

SELECT DISTINCT [First Name], [Last Name], [Product Name] FROM [Temp Test Data]

WHERE ([First Name] NOT IN (SELECT [First Name] 

FROM [Real Data]))

I'm having trouble taking this further though.

Thanks!

EDIT:

Based on the answer by @treaschf I have been trying to use a variation of the following query:

SELECT td.[First Name], td.[Last Name], td.[Product Name]

FROM [Temp Test Data] td FULL OUTER JOIN [Data] AS d 

ON td.[First Name] = d.[First Name] AND td.[Last Name] = d.[Last Name] 

WHERE (d.[First Name] = NULL) AND (d.[Last Name] = NULL)

But I keep getting 0 results back when I know that there is at least 1 row in td that is not in d.

EDIT:

Ok, I think I figured it out. At least in my few minutes of testing, it seems to work good enough.

SELECT [First Name], [Last Name]

FROM [Temp Test Data] AS td

WHERE (NOT EXISTS

(SELECT [First Name], [Last Name]

FROM [Data] AS d

WHERE ([First Name] = td.[First Name]) OR ([Last Name] = td.[Last Name])))

This is basically going to tell me what is in my test data that is not in my real data. Which is completely fine for what I need to do.

1 Answer

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by (40.4k points)

Let's say you are working on tables A and B, and if both the tables have column C. 

Rows/Records, which are present in table A but not in B are as follows:

SELECT A.*

FROM A

LEFT JOIN B ON (A.C = B.C)

WHERE B.C IS NULL

The full join must be used in order to get all the differences with a single query like this:

SELECT A.*, B.*

FROM A

FULL JOIN B ON (A.C = B.C)

WHERE A.C IS NULL OR B.C IS NULL

Note: When a record can be found in A, but not in B, then the columns which come from B will be NULL, 

and similarly, for those, which are present in B and not in  A, the columns from A will be null.

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