Subquery using Exists 1 or Exists *

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I used to write my EXISTS checks like this:

IF EXISTS (SELECT * FROM TABLE WHERE Columns=@Filters)
BEGIN
   UPDATE TABLE SET ColumnsX=ValuesX WHERE Where Columns=@Filters
END

One of the DBA's in a previous life told me that when I do an EXISTS clause, use SELECT 1 instead of SELECT *

IF EXISTS (SELECT 1 FROM TABLE WHERE Columns=@Filters)
BEGIN
   UPDATE TABLE SET ColumnsX=ValuesX WHERE Columns=@Filters
END

Does this really make a difference?

6 Answers
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