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Posted by SQL on 06/21/06 17:23
Run this in query analyzer
select * from
(select 1 as id)a
cross join (select 2 as id) b
as you can see the result set is this
id id
----------- -----------
1 2
id is displayed twice, where do you get id1 is it client site?
I ran the same query in enterprise manager and I see id twice
Denis the SQL Menace
http://sqlservercode.blogspot.com/
Mike S wrote:
> Hi all,
>
> A (possibly dumb) question, but I've had no luck finding a definitive
> answer to it. Suppose I have two tables, Employees and Employers, which
> both have a column named "Id":
>
> Employees
> -Id
> -FirstName
> -LastName
> -SSN
> etc.
>
> Employers
> -Id
> -Name
> -Address
> etc.
>
> and now I perform the following join:
>
> SELECT Employees.*, Employers.*
> FROM Employees LEFT JOIN Employers ON (Employees.Id=Employers.Id)
>
> The result-set will contain two "Id" columns, so SQL Server will
> disambiguate them; one column will still be called "Id", while the
> other will be called "Id1." My question is, how are you supposed to
> know which "Id" column belongs to which table? My intuition tells me,
> and limited testing seems to indicate, that it depends on the order in
> which the table names show up in the query, so that in the above
> example, "Id" would refer to Employees.Id, while "Id1" would refer to
> Employers.Id. Is this order guaranteed?
>
> Also, why does SQL Server use such a IMO brain-damaged technique to
> handle column name conflicts? In MS Access, it's much more
> straightforward; after executing the above query, you can use
> "Employees.Id" and "Employers.Id" (and more generally,
> "TableNameOrTableAlias.ColumnName") to refer to the specific "Id"
> column you want, instead of "Id" and "Id1" -- the
> "just-tack-on-a-number" strategy is slightly annoying when dealing with
> complex queries.
>
> --
> Mike S
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