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 Find Customers Who Bought "A" and "B" But Not "C" (SQL Spackle) Rate Topic Display Mode Topic Options
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 Posted Wednesday, March 28, 2012 9:51 PM
 SSC-Forever Group: General Forum Members Last Login: Today @ 2:41 PM Points: 42,081, Visits: 39,473
 Comments posted to this topic are about the item Find Customers Who Bought "A" and "B" But Not "C" (SQL Spackle) --Jeff Moden"RBAR is pronounced "ree-bar" and is a "Modenism" for "Row-By-Agonizing-Row".First step towards the paradigm shift of writing Set Based code: Stop thinking about what you want to do to a row... think, instead, of what you want to do to a column." Helpful Links:How to post code problemsHow to post performance problems
Post #1274832
 Posted Wednesday, March 28, 2012 9:56 PM
 SSC Rookie Group: General Forum Members Last Login: Monday, November 28, 2016 6:23 AM Points: 48, Visits: 446
 @JeffDid you compare the speed of this query against one where your first (Group By) From clause is a Select Distinct (sub) query?Nice article. It builds nicely for the reader.I love seeing the Except clause being introduced to the reader who, like me, cut our teeth on SQL92 and need to learn newer language features to be more productive.
Post #1274833
 Posted Wednesday, March 28, 2012 10:17 PM
 SSC Veteran Group: General Forum Members Last Login: Friday, December 18, 2015 1:54 AM Points: 229, Visits: 231
 Another way to get the result would be to use Intersect and then combine it with Except. The distinct part is handled implicitly.`--===== Find Customers that bought both "A" AND "B" SELECT CustomerID FROM #Purchase WHERE ProductCode IN ('A')INTERSECT SELECT CustomerID FROM #Purchase WHERE ProductCode IN ('B')EXCEPT--===== Find Customers that bought "C". SELECT CustomerID FROM #Purchase WHERE ProductCode IN ('C');`
Post #1274836
 Posted Wednesday, March 28, 2012 10:53 PM
 SSCommitted Group: General Forum Members Last Login: Tuesday, February 17, 2015 6:07 AM Points: 1,526, Visits: 2,000
 Wouldnt something like this work just as well?`SELECT CustomerIdFROM #PurchaseWHERE ProductCode IN ('A','B', 'C')GROUP BY CustomerIDhaving sum(case when ProductCode = 'A' then 1 else 0 end) > 0 and sum(case when ProductCode = 'B' then 1 else 0 end) > 0 and sum(case when ProductCode = 'C' then 1 else 0 end) = 0`/T
Post #1274846
 Posted Wednesday, March 28, 2012 11:04 PM
 SSCrazy Group: General Forum Members Last Login: Saturday, November 19, 2016 1:44 PM Points: 2,271, Visits: 5,545
 tommyh (3/28/2012)Wouldnt something like this work just as well?`SELECT CustomerIdFROM #PurchaseWHERE ProductCode IN ('A','B', 'C')GROUP BY CustomerIDhaving sum(case when ProductCode = 'A' then 1 else 0 end) > 0 and sum(case when ProductCode = 'B' then 1 else 0 end) > 0 and sum(case when ProductCode = 'C' then 1 else 0 end) = 0`/TYep, this is how i once implemented it! Cant remember the thread now.Here it is: http://www.sqlservercentral.com/Forums/FindPost1267224.aspxProved to elimate the EXCEPT part; also does a single scan on the table.
Post #1274850
 Posted Wednesday, March 28, 2012 11:53 PM
 SSCoach Group: General Forum Members Last Login: Today @ 1:35 AM Points: 15,510, Visits: 13,170
 Nice spackle Jeff, and great alternatives in the discussion! How to post forum questions.Need an answer? No, you need a question.What’s the deal with Excel & SSIS?Member of LinkedIn. My blog at SQLKover. MCSA SQL Server 2012 - MCSE Business Intelligence
Post #1274872
 Posted Wednesday, March 28, 2012 11:55 PM
 SSCrazy Group: General Forum Members Last Login: Saturday, November 19, 2016 1:44 PM Points: 2,271, Visits: 5,545
 OH yeah, Nice one Jeff. As always! Thanks a lot for taking time to teach us some of the tricks of the game. Thaks a lot :)
Post #1274873
 Posted Thursday, March 29, 2012 12:37 AM
 SSC-Addicted Group: General Forum Members Last Login: Sunday, October 9, 2016 3:59 PM Points: 461, Visits: 668
 Had a play with this and was very impressed - nice job. I played around and added this index `CREATE INDEX IX_#Purchase_ProductCode ON #Purchase ( ProductCode) INCLUDE (CustomerID)`One concern I had was looking at the query plan, the EXCEPT does a clustered index scan. That may be a function of the small data set, but I am not sure.My preference for these types of queries has always been to do an OUTER JOIN on the one we don't want selected and then say that we only want the ones that didn't match returned.`SELECT a.CustomerID FROM #Purchase a LEFT OUTER JOIN #Purchase b ON b.CustomerID = a.CustomerID AND b.ProductCode IN ('C') WHERE a.ProductCode IN ('A','B') AND b.CustomerID IS NULL GROUP BY a.CustomerID HAVING COUNT(DISTINCT a.ProductCode) = 2`Any thoughts?
Post #1274889
 Posted Thursday, March 29, 2012 1:07 AM
 Grasshopper Group: General Forum Members Last Login: Monday, July 15, 2013 6:08 PM Points: 14, Visits: 73
 "Left Join Where Is Null" gets complicated to read/understand and is subject to cardinalities issues that will impact performance if the right set has many records for 1 record in the left hand side.There is also this way, probably the closest to natural language.`Select Distinct CustomerIDFrom #PurchaseWhere ProductCode = 'A'And CustomerID In( Select CustomerID From #Purchase Where ProductCode = 'B')And CustomerID Not In( Select CustomerID From #Purchase Where ProductCode = 'C')`I would be interested to have this table filled by 100,000+ rows of sample data and then compare execution plans and statistics of the proposed approaches.Comparing syntax without an idea of the performance signature is a bit useless IMHO.So here is another version of the initialization script from which the difference will be more blatant:`--===== Conditionally drop the test table to make -- reruns in SSMS easier. IF OBJECT_ID('tempdb..#Purchase','U') IS NOT NULL DROP TABLE #Purchase;--===== Create the test table CREATE TABLE #Purchase ( PurchaseID INT IDENTITY(1,1), CustomerID INT, ProductCode VARCHAR(1000) PRIMARY KEY CLUSTERED (PurchaseID) );--===== Populate the test table with known data. INSERT INTO #Purchase (CustomerID, ProductCode)------- Customer #1 precisely meets the criteria. -- Bought 'A' and 'B' but not 'C'. SELECT 1, 'A' UNION ALL SELECT 1, 'B' UNION ALL------- Customer #2 also meets the criteria. -- Bought 'A' and 'B' and somthing else, -- but not 'C'. SELECT 2, 'A' UNION ALL SELECT 2, 'B' UNION ALL SELECT 2, 'D' UNION ALL------- Customer #3 also meets the criteria. -- Bought 'A' and 'B' and something else, -- but not 'C'. SELECT 3, 'A' UNION ALL SELECT 3, 'B' UNION ALL SELECT 3, 'D' UNION ALL SELECT 3, 'A' UNION ALL SELECT 3, 'D' UNION ALL------- Customer #4 doesn't meet the criteria. -- Bought 'A' and 'B' but also bought 'C'. SELECT 4, 'A' UNION ALL SELECT 4, 'B' UNION ALL SELECT 4, 'C' UNION ALL------- Customer #5 doesn't meet the criteria. -- Bought 'A' and 'B' and something else, -- but also bought 'C'. SELECT 5, 'A' UNION ALL SELECT 5, 'B' UNION ALL SELECT 5, 'A' UNION ALL SELECT 5, 'B' UNION ALL SELECT 5, 'C' UNION ALL SELECT 5, 'D' UNION ALL------- Customer #6 doesn't meet the criteria. -- Bought more than 1 of 'A' and something else -- but not 'B'. SELECT 6, 'A' UNION ALL SELECT 6, 'A' UNION ALL SELECT 6, 'D' UNION ALL SELECT 6, 'E' UNION ALL------- Customer #7 doesn't meet the criteria. -- Bought more than 1 of 'B' and something else -- but not 'A'. SELECT 7, 'B' UNION ALL SELECT 7, 'B' UNION ALL SELECT 7, 'D' UNION ALL SELECT 7, 'E'godeclare @i int = 10;while @i < 100000begin insert into #Purchase (CustomerID, ProductCode) select CustomerID + @i, ProductCode + Left(ProductCode, 1) From #Purchase set @i = @i * 2end`Then turn on statistics or open your SQL profiler`SET STATISTICS IO ON`And now you're ready.Then you will also need an index on ProductCode.`Create Index IX_ProductCode On #Purchase (ProductCode) Include (CustomerID);`
Post #1274898
 Posted Thursday, March 29, 2012 2:23 AM
 SSC Rookie Group: General Forum Members Last Login: Monday, August 4, 2014 5:14 AM Points: 27, Visits: 52
 How about this? Although i agree query might get longer when there would be more than 3 items` SELECT DISTINCT CustomerID FROM #Purchase P WHERE EXISTS (SELECT 1 FROM #Purchase P1 WHERE P.customerid = P1.customerid AND P1.productcode = 'A' ) AND EXISTS (SELECT 1 FROM #Purchase P2 WHERE P.customerid = P2.customerid AND P2.productcode = 'B' ) AND NOT EXISTS (SELECT 1 FROM #Purchase P3 WHERE P.customerid = P3.customerid AND P3.productcode = 'C' )`
Post #1274924

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