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Create a comma-separated string from multiple rows of one column?

开发者 https://www.devze.com 2023-04-12 21:59 出处:网络
I\'ve an access table like this ID | UserName | CarBrand ------------------------开发者_高级运维-

I've an access table like this

ID | UserName | CarBrand
------------------------开发者_高级运维-
0    Peter      VW
1    Peter      Ferrari
2    Mike       Audi
3    Peter      Dodge
4    Heidi      BMW
5    Heidi      Ford

I need the names from the CarBrand field as a comma separated list for a report.

Is there a way (without VB, maybe using a COALESCE alternative?) to create a comma-separated string like this, without the Name: part?

Peter: VW, Ferrari, Dodge
Mike:  Audi
Heidi: BMW, Ford

As it's for a report are there any other ways to do this, maybe using expressions in the report?


You cannot do this is Access without VBA. Coalesce does not exist, but you can write a UDF that has some of the functionality, for example http://allenbrowne.com/func-concat.html However, once you use a UDF, the query is no longer viable outside Access.


Create a main report with a unique list of usernames.

Create a sub report with a list of usernames and their Car Brands. Join the forms on the UserName. In the design of the subform, use 4-5 columns which print horizontally. You can have the CarBrand field include a formula like =[CarBrand] & ", " (Sorry the last one is going to have an unecessary comma. They will be spaced accross uniformly and will break into a new row if a particular user has more brands than can fit accross you report (Which will be real hard to do if you just create one large comma-separated string.).

No VBA involved at all.


If you do not need every single value in your comma delimited list, but say just up to the first 3 or 4 or so, then there is a pure SQL solution in Access.

I am working on a DB for a non-profit that has Tutors and Classes. For most classes, there is just 1 or 2 tutors. For display purposes, I can't list more than 2 or 3 anyway, so I am not worried about truncating outliers with 5 or more tutors.

This will grab the 3 tutors for each class with the lowest Tutor IDs

Select JTC1.ClassID, Min(JTC1.TID1) as TutorID1,
  Min(JTC1.TID2) as TutorID2,
  Min(JTC1.TID3) as TutorID3 
from (
  Select distinct TC1.ClassID,
    TC1.TutorID as TID1,
    TC2.TutorID as TID2,
    TC3.TutorID as TID3 
  from ((
   Classes C 
   Left Join TutorClasses TC1 
     on C.ClassID = TC1.ClassID)
   Left Join TutorClasses TC2 
     on TC1.ClassID = TC2.ClassID and TC1.TutorID < TC2.TutorID
   )
   Left Join TutorClasses TC3
     on TC2.ClassID = TC3.ClassID and TC2.TutorID < TC3.TutorID
   ) as JTC1
Group by JTC1.ClassID

Obviously, 1 extra step (not shown) will be needed to combine the three columns into 1.

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