Re: Comparing two tables of different database

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От John Zhang
Тема Re: Comparing two tables of different database
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Msg-id 618950b80905010855y70609c47j187f16967ab0da77@mail.gmail.com
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Ответ на Re: Comparing two tables of different database  ("Edward W. Rouse" <erouse@comsquared.com>)
Ответы Re: Comparing two tables of different database  (Wei Weng <wweng@kencast.com>)
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Hi Nicholas,

The query is across database query.  dblink is needed for that task.

Hope it helps,

John

On Thu, Apr 30, 2009 at 3:07 PM, Edward W. Rouse <erouse@comsquared.com> wrote:

Can’t you use this?

 

select name from database2.sr_1 where name not in (select name from database2.pr_1);

 

My test database VM isn’t running so I can’t test it, but I seem to remember that that’s how I did it for a few queries of that type. This is assuming the 2 databases are running on the same machine, like the way there is template0 as the default and you add addition databases to the same ‘instance’. If you are talking about 2 different database servers, then I have no idea.

 

Edward W. Rouse

 

From: pgsql-sql-owner@postgresql.org [mailto:pgsql-sql-owner@postgresql.org] On Behalf Of Nicholas I
Sent: Thursday, April 30, 2009 6:12 AM
To: Joshua Tolley
Cc: Adam Ruth; Pawel Socha; pgsql-sql@postgresql.org
Subject: Re: [SQL] Comparing two tables of different database

 

Hi All,

  For example,

    There are two database.   database1 and database 2;
   
     database1 has a table called pr_1 with the columns, id,name and time.
     database2 has a table called sr_1 with the_columns id,name and time.
  
     i would like to find out the differences that is, find the names that are not in sr_1 but in pr_1.
     we can achieve this by the query,
  
         select name from sr_1 where name not in (select name from pr_1);
    the above query will work in case of two tables in the same database.


     But the problem is, these two tables are in different database. i did not understand about the dblink.

    is there any exaples on dblink. can we do it without using dblink.

-Nicholas I
   
     


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