Get unique poolID value for interlinked items

18 Aug 2006 1:15 PM

Veeraraje Urs

Hi All

    I have a table with the data in the following format
           Col1 Col2 PoolID
      BOOK1 BOOK2 0
      BOOK3 BOOK1 0
      BOOK3 BOOK4 0
      BOOK5 BOOK6 0

As per the above data our business logic says that
                                       Book1 is linked with Book2
                                and Book3 is linked with Book1
                                and Book3 is linked with Book4

Since Book1 is linked with Book2 and
          Book1 is linked with Book3
as per our business logic, Book2 is also linked with Book3

So going by the above rule, Book1, Book2, Book3 and Book4 are linked each
other.
Our requirement is that we need to identify these interlinked items and
update the poolid

So the net result will be Book1, Book2, Book3 and Book4 will have a value of
1
    and Book5 and Book6 will have a value of 2

Script for creating the table :

CREATE TABLE TABLE_A
(Col1 varchar(255),
Col2 varchar(255),
PoolID int)
GO
INSERT INTO TABLE_A
SELECT 'BOOK1', 'BOOK2',0
GO
INSERT INTO TABLE_A
SELECT 'BOOK3', 'BOOK1',0
GO
INSERT INTO TABLE_A
SELECT 'BOOK3', 'BOOK4',0
O
INSERT INTO TABLE_A
SELECT 'BOOK5', 'BOOK6',0
GO

Select * from Table_A
--Drop table Table_A

Kindly Help

Thanks
Veeraraje Urs

18 Aug 2006 11:10 PM

Hugo Kornelis

On Fri, 18 Aug 2006 18:45:51 +0530, Veeraraje Urs wrote:

Show quote

>Hi All
>
>    I have a table with the data in the following format
>           Col1 Col2 PoolID
>      BOOK1 BOOK2 0
>      BOOK3 BOOK1 0
>      BOOK3 BOOK4 0
>      BOOK5 BOOK6 0
>
>
>As per the above data our business logic says that
>                                       Book1 is linked with Book2
>                                and Book3 is linked with Book1
>                                and Book3 is linked with Book4
>
>Since Book1 is linked with Book2 and
>          Book1 is linked with Book3
>as per our business logic, Book2 is also linked with Book3
>
>So going by the above rule, Book1, Book2, Book3 and Book4 are linked each
>other.
>Our requirement is that we need to identify these interlinked items and
>update the poolid
>
>So the net result will be Book1, Book2, Book3 and Book4 will have a value of
>1
>    and Book5 and Book6 will have a value of 2

Hi Veeraraje Urs,

Do the values have to be 1 and 2, or do they just have to be two
different values? In the latter case, try this:

WITH X (Col1, Col2, PoolID, rn)
AS   (SELECT Col1, Col2, PoolID,
               ROW_NUMBER() OVER (ORDER BY Col1, Col2) AS rn
        FROM   TABLE_A)
UPDATE X
SET    PoolID = X.rn;

WHILE (@@ROWCOUNT > 0)
BEGIN;
UPDATE TABLE_A
SET PoolID = (SELECT MIN(x.PoolID)
                FROM   TABLE_A AS x
                WHERE x.Col1 IN (TABLE_A.Col1, TABLE_A.Col2)
                OR     x.Col2 IN (TABLE_A.Col1, TABLE_A.Col2))
WHERE PoolID <> (SELECT MIN(x.PoolID)
                   FROM   TABLE_A AS x
                   WHERE x.Col1 IN (TABLE_A.Col1, TABLE_A.Col2)
                   OR     x.Col2 IN (TABLE_A.Col1, TABLE_A.Col2));
END;

The first part (which uses a SQL Server 2005 function - let me know if
you need a SQL Server 2000 equivalent) assigns a unique PoolID to each
row in the table. The next part (which should run on all versions of SQL
Server) replaces each PoolID with the lowest PoolID from any interlinked
item, and repeats this in a loop until no more changes are made.

--
Hugo Kornelis, SQL Server MVP

19 Aug 2006 9:42 AM

amish

Hugo Kornelis wrote:

Show quote

> On Fri, 18 Aug 2006 18:45:51 +0530, Veeraraje Urs wrote:
>
> >Hi All
> >
> >    I have a table with the data in the following format
> >           Col1 Col2 PoolID
> >      BOOK1 BOOK2 0
> >      BOOK3 BOOK1 0
> >      BOOK3 BOOK4 0
> >      BOOK5 BOOK6 0
> >
> >
> >As per the above data our business logic says that
> >                                       Book1 is linked with Book2
> >                                and Book3 is linked with Book1
> >                                and Book3 is linked with Book4
> >
> >Since Book1 is linked with Book2 and
> >          Book1 is linked with Book3
> >as per our business logic, Book2 is also linked with Book3
> >
> >So going by the above rule, Book1, Book2, Book3 and Book4 are linked each
> >other.
> >Our requirement is that we need to identify these interlinked items and
> >update the poolid
> >
> >So the net result will be Book1, Book2, Book3 and Book4 will have a value of
> >1
> >    and Book5 and Book6 will have a value of 2
>
> Hi Veeraraje Urs,
>
> Do the values have to be 1 and 2, or do they just have to be two
> different values? In the latter case, try this:
>
> WITH X (Col1, Col2, PoolID, rn)
>   AS   (SELECT Col1, Col2, PoolID,
>                ROW_NUMBER() OVER (ORDER BY Col1, Col2) AS rn
>         FROM   TABLE_A)
> UPDATE X
> SET    PoolID = X.rn;
>
> WHILE (@@ROWCOUNT > 0)
>   BEGIN;
>   UPDATE TABLE_A
>   SET PoolID = (SELECT MIN(x.PoolID)
>                 FROM   TABLE_A AS x
>                 WHERE x.Col1 IN (TABLE_A.Col1, TABLE_A.Col2)
>                 OR     x.Col2 IN (TABLE_A.Col1, TABLE_A.Col2))
>   WHERE PoolID <> (SELECT MIN(x.PoolID)
>                    FROM   TABLE_A AS x
>                    WHERE x.Col1 IN (TABLE_A.Col1, TABLE_A.Col2)
>                    OR     x.Col2 IN (TABLE_A.Col1, TABLE_A.Col2));
>   END;
>
> The first part (which uses a SQL Server 2005 function - let me know if
> you need a SQL Server 2000 equivalent) assigns a unique PoolID to each
> row in the table. The next part (which should run on all versions of SQL
> Server) replaces each PoolID with the lowest PoolID from any interlinked
> item, and repeats this in a loop until no more changes are made.
>
> --
> Hugo Kornelis, SQL Server MVP

If you are using SQL Server 2005 then you can try this query

WITH temp (Col1, Col2, id)
AS   (SELECT Col1, Col2,
               ROW_NUMBER() OVER (ORDER BY Col1, Col2) AS num
        FROM   TABLE_A) ,

t as
(select col1 , col2,id,1 as poolid from temp where id= 1
union all
select temp.col1 , temp.col2,temp.id, case when
(temp.col1 in (t.col1, t.col2) or
temp.col2 in (t.col1, t.col2) ) then poolid
else poolid + 1 end
from temp , t
where temp.id= t.id+1
)

update table_a set poolid = t.poolid
from t
where t.col1 = table_a.col1 and
t.col2 = table_a.col2
go
select * from table_a

First it assigns row_number and then it use common table expression ,
both are sql server 2005 features.

Regards
Amish Shah
http://shahamishm.tripod.com