UNION

UNION vs. UNION ALL in SQL Server

  • Article

Sometimes there is a need to combine data from multiple tables or views into one comprehensive dataset. This may be for like tables within the same database or maybe there is a need to combine like data across databases or even across servers. I have read about the UNION and UNION ALL commands, but how do these work and how do they differ?

2019-12-05

Union Forcing Distinct

  • Script

The use of union would seem to force a distinct in each of the select statements being unioned. The use multiple unions, with mixed union and union all clauses, seems to cause haphazard results.

1.67 (3)

2013-05-14 (first published: )

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