From: | Bruce Momjian <maillist(at)candle(dot)pha(dot)pa(dot)us> |
---|---|
To: | sferac(at)proxy(dot)bazzanese(dot)com (Jose' Soares Da Silva) |
Cc: | pgsql-hackers(at)postgreSQL(dot)org, pgsql-docs(at)postgreSQL(dot)org |
Subject: | Re: [HACKERS] Reference Manual] |
Date: | 1998-03-30 15:25:03 |
Message-ID: | 199803301525.KAA13181@candle.pha.pa.us |
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Thread: | |
Lists: | pgsql-hackers |
> 2. - Seems that optional ALL keyword of UNION doesn't work.
> The following query prints always the same result with and without
> the ALL clause.
>
> * UNION of two tables:
>
> mytable: yourtable:
> id|name id|name
> --+------ --+------
> 1|Smith 1|Soares
> 2|Jones 2|Panini
> 3|Soares
>
>
> SELECT mytable.id, mytable.name
> FROM mytable
> WHERE mytable.name LIKE 'S%'
> UNION
> SELECT yourtable.id, yourtable.name
> FROM yourtable
> WHERE yourtable.name LIKE 'S%';
>
> this is the result even if I don't specify ALL.
> id|name
> --+------
> 1|Smith
> 1|Soares
> 3|Soares
The second column is duplicate, but the first is not. It looks at all
columns to determine duplicates.
--
Bruce Momjian | 830 Blythe Avenue
maillist(at)candle(dot)pha(dot)pa(dot)us | Drexel Hill, Pennsylvania 19026
+ If your life is a hard drive, | (610) 353-9879(w)
+ Christ can be your backup. | (610) 853-3000(h)
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