Understanding UNION and UNION ALL in SQL Server
A short look at the differences in UNION and UNION ALL in a SELECT query.
2025-04-07
4,441 reads
A short look at the differences in UNION and UNION ALL in a SELECT query.
2025-04-07
4,441 reads
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
Paul White digs into row goals as he explains some interesting and inconsistent behavior with UNION ALL queries in SQL Server.
2017-06-13
5,896 reads
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I have added a few indexes to one of my tables in SQL Server 2025:
ALTER TABLE dbo.CustomerContact
ADD CONSTRAINT PK_CustomerContact
PRIMARY KEY (CustomerID);
-- Create index on CustomerEmail
CREATE INDEX IX_CustomerContact_CustomerEmail
ON dbo.CustomerContact (CustomerEmail);
CREATE INDEX IX_CustomerContact_CustomerPhone
ON dbo.CustomerContact (phone);
I then do this to disable one index:
alter index IX_CustomerContact_CustomerPhone on dbo.CustomerContact disableI see this when I check the index status:
I decide to rebuild all indexes with this command:
ALTER INDEX ALL ON dbo.CustomerContact rebuildAfter I do this, what will I see for the index status? See possible answers