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Joining tables from different sources
Submitted by Joseph DAnna on October 28th, 2008
Is it possible to join tables from different data connections for analysis on a single sheet. What I am trying to do in this specific case is combine data from a .CSV file, that I have loaded into Tableau, with data from a connection with an Access database that contains related information. What about combining data on one sheet from a postgresql db and a MS access one?
thanks,
Joe
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October 28th, 2008
mcristia
Posts: 201
Joined March 2008
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Joe,
The Tableauites will correct me if I am incorrect on this, but I think I have seen somewhere on here something like this scenario.
1. In your access database, import the .CSV as a linked table. Tableau will see it, then.
2. Join it as you wish with other tables in your Access database.
3. Wait....wait....maybe wait some more?
Michael
October 28th, 2008
Erin Easter
Posts: 397
Joined October 2007
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Hi Joe,
Michael's technique described above will work for local file data sources like MS Access, Excel, and CSV. However, when you get into data sources like PostgreSQL, MySQL, etc. you cannot join from one database type to another. Data that you have in in MS Access or CSV that you want to join into the PostgreSQL database will have to be combined as multiple tables in a single database.
-Erin
October 28th, 2008
mcristia
Posts: 201
Joined March 2008
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Erin,
Sorry for the ambiguity -- I think I knew that but had a memory leak over here.
Michael
December 18th, 2008
designerweb
Posts: 7
Joined December 2008
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I have two MSSQL Databases and I'm trying to connect them on joins... I'm not sure how I can add both datasources.
They are two different databases but they reside on the same server.
So serverX
has both
Db1 & Db2 on it
I want to connect Db1 to Db2 on Db1.table.fieldCommon = Db2.table.fieldCommon
Can I do this in tableau?
Thanks,
David
December 18th, 2008
James Baker
Posts: 673
Joined December 2007
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Sorry, David. Joins work on tables, not on databases. Tableau doesn't offer cross-datasource merges/joins yet - it has to be able to see them as one database in order to join tables.
June 5th, 2009
jgmiller
Posts: 2
Joined October 2008
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This answer is a little late but maybe it will help. We have the same situation on a mySQL server. Multiple databases and we want to join tables across them. We've found two ways to do this.
1. Use a custom SQL statement, this is obviously not the ideal situation if the person doing it isn't that good with SQL
2. At the filesystem level use symbolic links. Say you've got table A in DB1 and table B in DB2 and you want to join A & B. If you create symbolic links for the mySQL files comprising the table A in DB2 then restart mySQL the server will happily report that A exists in both DB1 and DB2. The dangerous part is that you can't allow updates to occur on the linked table in DB2, it can only be used for queries.
John
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