select distinct from multiple tables

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January 8th, 2004, 09:46 AM

dmors

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Join Date: Jan 2004

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select distinct from multiple tables

I have three tables "items", "dates", "membership", and "collection".

"items" joins "dates" on Id, a unique identifier. "collection" defines certain collections of "items", each has a unique collection_id. So "membership" has an Id field, and a collection_id field. Each "items" record can belong to multiple "collection"s.

The query:

Code:

SELECT i.Id, i.Name, d.Date from items as i LEFT JOIN dates as d on (i.Id = d.Id) LEFT JOIN membership as m on (i.Id = m.Id) LEFT JOIN collection as c on (m.collection_id = c.collection_id)

returns the expected results, but I need to only get ONE of each "items" record, regardless of how many memberships it has. The membership record it returns is unimportant. I tried DISTINCT, but I'm not sure I have the syntax down right, and can't seem to find documentation or a sample that applies to this situation.

In another forum, Stumpy suggested:

Code:

SELECT DISTINCT(i.Id), i.Name, d.Date...

but it didn't work as I had hoped, meaning that it didn't limit it as I needed. Is there any other possible solution?

Also, if this isn't implied by my choice of forum: I have to accomplish this all with the SQL, I can't use ASP/PHP/Perl/anything else to accomplish this.

Thanks much for any help.

D. Mors

January 9th, 2004, 01:56 AM

r937

SQL Consultant

Join Date: Feb 2003

Location: Toronto Canada

Posts: 17,690

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you haven't really explained what you're trying to do

you say your query gets the expected results except more than one row per item -- well, that's becaise each item row is being joined to membership and collection rows

if all you really want is one row per item, do this:

Code:

select i.Id, i.Name, d.Date 
  from items as i 
left outer
   join dates as d 
     on i.Id = d.Id

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