data-konzept

'The UNION, INTERSECT, and EXCEPT clauses are used to combine or exclude like rows from two or more tables.  They are useful when you need to combine the results from separate queries into one single result.  They differ from a join in that entire rows are matched and, as a result, included or excluded from the combined result.'

http://www.essentialsql.com/learn-to-use-union-intersect-and-except-clauses/

also see...

https://www.simple-talk.com/sql/performance/the-except-and-intersect-operators-in-sql-server/

https://www.mssqltips.com/sqlservertip/1327/compare-sql-server-datasets-with-intersect-and-except/