Re: Search for lists

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От F. BROUARD / SQLpro
Тема Re: Search for lists
Дата
Msg-id 4DFE4892.1090004@club-internet.fr
обсуждение исходный текст
Ответ на Search for lists  (Daron Ryan <daron.ryan@gmail.com>)
Список pgsql-general
Le 18/06/2011 23:51, Daron Ryan a écrit :
>
> Hello,
>
> I need to search a table to find sets of rows that have a column
> matching itself for the whole set and another column matching row for
> row with a list I am going to supply. The result I should receive should
> be value of the column that matches itself.
>
> For example given the following data in my table:
>
> 3; 1
> 3; 2
> 4; 8
> 4; 9
> 4; 10
>
> I might need to search for 1,2. This should produce the result 3. Or if
> I were to search for 8, 9, 10 the result should be 4. Searching for 8, 9
> should produce an empty result as should 8, 9, 10, 11.
>
> Can anyone recommend a strategy?
>

this is a general case of relationnal division.

One way to do this is :


WITH
T0 AS
(SELECT 1 AS N --> all the data to be search each on a separate SELECT
  UNION ALL     --> with UNION ALL
  SELECT 2 AS N)
SELECT TBL_ID
FROM   T_MY_TABLE_TBL AS T
        INNER JOIN T0
              ON T.TBL_VALUE = T0.N
GROUP  BY TBL_ID
HAVING COUNT(*) = (SELECT COUNT(*)
                    FROM T0);

I you read french, I wrote a paper on the relational division :

http://sqlpro.developpez.com/cours/divrelationnelle/

A +

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