article Joins and Lookups in Member Articles https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/ta-p/1486428 <HTML><HEAD></HEAD><BODY><P>This document concerns data modelling and joins</P><UL><LI>What is the difference between a join using the join prefix and a join using a SELECT statement?</LI><LI>When should you join and when shouldn't you? Performance considerations?</LI><LI>Are there alternatives to joins? (Yes! Applymap!)</LI><LI>What does the Keep prefix do?</LI></UL><P></P><P><A _jive_internal="true" href="https://community.qlik.com/people/hic/content">HIC</A></P><P></P><P><SPAN>See also my blog post on the same subject: <A _jive_internal="true" href="https://community.qlik.com/blogs/qlikviewdesignblog/2012/09/12/to-join-or-not-to-join">To Join or not to Join</A>. </SPAN></P></BODY></HTML> Wed, 12 Sep 2012 12:01:01 GMT hic 2012-09-12T12:01:01Z Joins and Lookups https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/ta-p/1486428 <HTML><HEAD></HEAD><BODY><P>This document concerns data modelling and joins</P><UL><LI>What is the difference between a join using the join prefix and a join using a SELECT statement?</LI><LI>When should you join and when shouldn't you? Performance considerations?</LI><LI>Are there alternatives to joins? (Yes! Applymap!)</LI><LI>What does the Keep prefix do?</LI></UL><P></P><P><A _jive_internal="true" href="https://community.qlik.com/people/hic/content">HIC</A></P><P></P><P><SPAN>See also my blog post on the same subject: <A _jive_internal="true" href="https://community.qlik.com/blogs/qlikviewdesignblog/2012/09/12/to-join-or-not-to-join">To Join or not to Join</A>. </SPAN></P></BODY></HTML> Wed, 12 Sep 2012 12:01:01 GMT https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/ta-p/1486428 hic 2012-09-12T12:01:01Z Re: Joins and Lookups https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486429#M1953 <HTML><HEAD></HEAD><BODY><P>Well done, very informative!</P><P></P><P>Thanks, </P><P>Stefan</P></BODY></HTML> Sat, 15 Sep 2012 12:14:08 GMT https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486429#M1953 swuehl 2012-09-15T12:14:08Z Re: Joins and Lookups https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486430#M1954 <HTML><HEAD></HEAD><BODY><P>Awesome insights!</P></BODY></HTML> Tue, 20 Aug 2013 11:51:14 GMT https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486430#M1954 2013-08-20T11:51:14Z Re: Joins and Lookups https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486431#M1955 <HTML><HEAD></HEAD><BODY><P>This is great !!!</P></BODY></HTML> Tue, 20 Aug 2013 16:46:57 GMT https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486431#M1955 phaneendra_kunc 2013-08-20T16:46:57Z Re: Joins and Lookups https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486432#M1956 <HTML><HEAD></HEAD><BODY><P>Thank you! very helpful.</P></BODY></HTML> Tue, 20 Aug 2013 21:27:24 GMT https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486432#M1956 2013-08-20T21:27:24Z Re: Joins and Lookups https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486433#M1957 <HTML><HEAD></HEAD><BODY><P>Good info on Lookups.</P></BODY></HTML> Tue, 20 Aug 2013 21:34:44 GMT https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486433#M1957 jtanajewski 2013-08-20T21:34:44Z Re: Joins and Lookups https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486434#M1958 <HTML><HEAD></HEAD><BODY><P>fair dinkum</P></BODY></HTML> Tue, 20 Aug 2013 22:51:41 GMT https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486434#M1958 2013-08-20T22:51:41Z Re: Joins and Lookups https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486435#M1959 <HTML><HEAD></HEAD><BODY><P>Great Post</P></BODY></HTML> Wed, 21 Aug 2013 04:32:13 GMT https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486435#M1959 khadeer 2013-08-21T04:32:13Z Re: Joins and Lookups https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486436#M1960 <HTML><HEAD></HEAD><BODY><P>Informative</P></BODY></HTML> Wed, 21 Aug 2013 05:48:29 GMT https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486436#M1960 2013-08-21T05:48:29Z Re: Joins and Lookups https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486437#M1961 <HTML><HEAD></HEAD><BODY><P>Very Nice!</P></BODY></HTML> Fri, 30 Aug 2013 04:26:19 GMT https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486437#M1961 2013-08-30T04:26:19Z Re: Joins and Lookups https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486438#M1962 <HTML><HEAD></HEAD><BODY><P>Very nice</P></BODY></HTML> Fri, 30 Aug 2013 06:50:42 GMT https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486438#M1962 michael_maeuser 2013-08-30T06:50:42Z Re: Joins and Lookups https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486439#M1963 <HTML><HEAD></HEAD><BODY><P>Excellent as usual</P><P>Fabrice</P></BODY></HTML> Thu, 14 Nov 2013 09:21:46 GMT https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486439#M1963 2013-11-14T09:21:46Z Re: Joins and Lookups https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486440#M1964 <HTML><HEAD></HEAD><BODY><P>Excellent Job Done... Very Useful.</P></BODY></HTML> Fri, 15 Nov 2013 17:42:51 GMT https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486440#M1964 MK_QSL 2013-11-15T17:42:51Z Re: Joins and Lookups https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486441#M1965 <HTML><HEAD></HEAD><BODY><P>Muy bueno.</P><P></P><P>Gracias</P></BODY></HTML> Thu, 09 Jan 2014 14:39:55 GMT https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486441#M1965 2014-01-09T14:39:55Z Re: Joins and Lookups https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486442#M1966 <HTML><HEAD></HEAD><BODY><P>Simple And Clear</P></BODY></HTML> Sat, 22 Feb 2014 18:30:34 GMT https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486442#M1966 2014-02-22T18:30:34Z Re: Joins and Lookups https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486443#M1967 <HTML><HEAD></HEAD><BODY><P>great job !</P></BODY></HTML> Wed, 18 Jun 2014 11:42:55 GMT https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486443#M1967 Anonymous 2014-06-18T11:42:55Z Re: Joins and Lookups https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486444#M1968 <HTML><HEAD></HEAD><BODY><P>Thank you very much</P></BODY></HTML> Wed, 18 Jun 2014 12:29:54 GMT https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486444#M1968 2014-06-18T12:29:54Z Re: Joins and Lookups https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486445#M1969 <HTML><HEAD></HEAD><BODY><P>Hi</P><P>1. I made two inline tables just to test the keep function. Left and inner keep works fine, but a pure keep does not work?&nbsp;&nbsp;&nbsp; </P><P></P><P>2. I am very confused, I thought that star schemes where recommended with Qlikview, but here normalization is recommended in most cases?</P><P></P><P>3. What happens in a join if only some of the data in the specific rows are the same?&nbsp;&nbsp;&nbsp;&nbsp; </P></BODY></HTML> Fri, 20 Jun 2014 13:08:39 GMT https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486445#M1969 2014-06-20T13:08:39Z Re: Joins and Lookups https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486446#M1970 <HTML><HEAD></HEAD><BODY><P>1. If you don't specify which type of Join, then it is "Outer". The same logic applies for Keep, but since "Outer Keep" doesn't make sense....</P><P>2. It is a trade-off. Snowflake scheme is in my opinion easiest to maintain and should therefore be used. But for large data sets, a star scheme outperforms the snowflake scheme. So, star scheme may then be the better option.</P><P>3. Depends on whether you use Outer, Left, Right or Inner Join.</P><P></P><P>HIC </P></BODY></HTML> Sat, 21 Jun 2014 19:46:22 GMT https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486446#M1970 hic 2014-06-21T19:46:22Z Re: Joins and Lookups https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486447#M1971 <HTML><HEAD></HEAD><BODY><P>thx: </P><P>1. ah okay, of course it does not makes sense then <IMG src="https://community.qlik.com/legacyfs/online/emoticons/happy.png" />&nbsp;&nbsp; Since it accept "keep" as single word in the code, marked as blue, I thought it would do something. So I guess it only evaluates single words.</P><P></P><P>2. I thought normalization was for large data set and complex systems. Does the star and snowflake only make sense with a fact/dimensional approach?&nbsp; </P><P></P><P>3. I will do some more testing <IMG src="https://community.qlik.com/legacyfs/online/emoticons/happy.png" />&nbsp;&nbsp; </P></BODY></HTML> Sun, 22 Jun 2014 07:49:55 GMT https://community.qlik.com/t5/Member-Articles/Joins-and-Lookups/tac-p/1486447#M1971 2014-06-22T07:49:55Z