Stairway to Advanced T-SQL Level 6: Creating Rows Of Data Using The UNPIVOT Operator

• Greg Larsen

  SSC-Insane

  Points: 20961

  More actions

  June 24, 2015 at 12:00 am

  #145760

  Comments posted to this topic are about the item Stairway to Advanced T-SQL Level 6: Creating Rows Of Data Using The UNPIVOT Operator

  Gregory A. Larsen, MVP

• g.britton

  SSChampion

  Points: 13863

  More actions

  June 24, 2015 at 7:19 am

  #1807727

  Greg Larsen (4/27/2015)

  ---

  Comments posted to this topic are about the item <A HREF="/articles/Stairway+Series/125504/">Stairway to Advanced T-SQL Level 6: Creating Rows Of Data Using The UNPIVOT Operator</A>

  Consider using CROSS APPLY instead of UNPIVOT. More flexible (can unpivot multiple columns at once) and can generate better plans.

  Unpivot a table using cross apply[/url]

  Gerald Britton, Pluralsight courses

• akljfhnlaflkj

  SSC Guru

  Points: 76202

  More actions

  June 25, 2015 at 7:21 am

  #1808050

  I'm still a little confused, but good start for me anyway.

• ChrisM@Work

  SSC Guru

  Points: 186127

  More actions

  June 25, 2015 at 7:45 am

  #1808063

  g.britton (6/24/2015)

  ---

  Greg Larsen (4/27/2015)

  ---

  Comments posted to this topic are about the item <A HREF="/articles/Stairway+Series/125504/">Stairway to Advanced T-SQL Level 6: Creating Rows Of Data Using The UNPIVOT Operator</A>

  Consider using CROSS APPLY instead of UNPIVOT. More flexible (can unpivot multiple columns at once) and can generate better plans.

  Unpivot a table using cross apply[/url]

  CROSS APPLY VALUES is a more specific term for the use of CROSS APPLY in a manual unpivot. Dwain's written a great article here[/url].

  ^{“Write the query the simplest way. If through testing it becomes clear that the performance is inadequate, consider alternative query forms.” - Gail Shaw}

  For fast, accurate and documented assistance in answering your questions, please read this article.
  Understanding and using APPLY, (I) and (II) Paul White
  Hidden RBAR: Triangular Joins / The "Numbers" or "Tally" Table: What it is and how it replaces a loop Jeff Moden

• g.britton

  SSChampion

  Points: 13863

  More actions

  June 30, 2015 at 6:31 am

  #1809086

  ChrisM@Work (6/25/2015)

  ---

  g.britton (6/24/2015)

  ---

  Greg Larsen (4/27/2015)

  ---

  Comments posted to this topic are about the item <A HREF="/articles/Stairway+Series/125504/">Stairway to Advanced T-SQL Level 6: Creating Rows Of Data Using The UNPIVOT Operator</A>

  Consider using CROSS APPLY instead of UNPIVOT. More flexible (can unpivot multiple columns at once) and can generate better plans.

  Unpivot a table using cross apply[/url]

  CROSS APPLY VALUES is a more specific term for the use of CROSS APPLY in a manual unpivot. Dwain's written a great article here[/url].

  Well it makes no difference if you use VALUES or SELECT with a UNION ALL. That is:

  with cte as

  (

  select 1 as one, 2 as two, 3 as three, 4 as four

  )

  select a, b

  from cte

  cross apply

  (

  select one, two

  union all

  select three, four

  --values (one,two),

  -- (three,four)

  ) upvt(a, b)

  works just the same if you comment the SELECTs in the cross apply and uncomment the VALUES. Granted, the second is a little less typing but the functionality is the same I believe (as is the actual execution plan, I think). I would even argue that the SELECT...UNION ALL is a little more flexible since you can add where clauses if needed

  Gerald Britton, Pluralsight courses