Re: join syntax

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От scott.marlowe
Тема Re: join syntax
Дата
Msg-id Pine.LNX.4.33.0306171253220.2647-100000@css120.ihs.com
обсуждение исходный текст
Ответ на join syntax  (Jodi Kanter <jkanter@virginia.edu>)
Ответы comparing querys  (Lucas Lain <lainl@aconectarse.com>)
Список pgsql-sql
On Tue, 17 Jun 2003, Jodi Kanter wrote:

> One of my colleagues has created a database where he has the same field 
> name in two tables and uses this field to link his tables rather than 
> some arbitrary value. For example, he has used "exp_id" in two tables. 
> When writing his joins he uses a syntax that says something like JOIN ON 
> EXP_ID. Can someone tell me what that syntax should be? I am not very 
> familiar with it since I typically use the syntax where one field is set 
> equal to the other.
> Personally I prefer not to set databases up this way but cannot seem to 
> convince him of this. And yet I am supposed to now help him with his 
> database and application.. Is there some documentation that would define 
> this type of syntax? How is this handled if you have more than one table 
> in the join? It does not appear that this format would allow for this.

If you're joining two tables on a field that has the same name you can use 
a natural join.

select * from table1 natural join table2;



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