Request: Help creating a difficult view.

[Dave Pylatuk]

Hello all.

I have a table defined in sql server as follows:

ROW_ID (identity)
DEPTH_FROM Number (8,3)
DEPTH_TO Number (8,3)
COLOUR Char(10)

With typical data like:
ROW_ID DEPTH_FROM DEPTH_TO COLOUR
---------------------------------------------------------------
1 0 5
BLUE
2 5 8
BLUE
3 8 10
RED
4 10 12
GREEN
5 12 16
GREEN

I want to create a view that will 'compress/roll up' the data so
it appears like:

DEPTH_FROM DEPTH_TO COLOUR
---------------------------------------------------------
0 8 BLUE
8 10 RED
10 16 GREEN

I have been working on this for several days, with no luck,
any help would be appreciated. BTW: there are no overlaps
allowed in the depth_from, depth_to values.

Thanks in advance.

[David Portas]

Re: Request: Help creating a difficult view.

I'll assume that the colours don't always occur at consecutive depths
otherwise you could just do this:

SELECT MIN(depth_from) , MAX(depth_to), colour
FROM ColDepths
GROUP BY colour


Here's the (assumed) DDL and sample data. It helps if you include this with
posts.

CREATE TABLE ColDepths (row_id INTEGER NOT NULL UNIQUE, depth_from INTEGER
NOT NULL, depth_to INTEGER NOT NULL, colour CHAR(10) NOT NULL,
CHECK(depth_fro m<depth_to), PRIMARY KEY (depth_from,dep th_to))

INSERT INTO ColDepths VALUES (1,0,5, 'BLUE')
INSERT INTO ColDepths VALUES (2,5,8, 'BLUE')
INSERT INTO ColDepths VALUES (3,8,10, 'RED')
INSERT INTO ColDepths VALUES (4,10,12, 'GREEN')
INSERT INTO ColDepths VALUES (5,12,16, 'GREEN')

Here's my query.

SELECT MIN(A.depth_fro m) AS depth_from,
MAX(A.depth_to) AS depth_to, A.colour
FROM ColDepths AS A
JOIN
(SELECT c1.row_id, MIN(C2.depth_to ) AS next_depth
FROM ColDepths AS C1
LEFT JOIN ColDepths AS C2
ON C1.colour <> C2.colour
AND (C1.depth_from < C2.depth_from
OR (C1.depth_from = C2.depth_from)
AND C1.depth_to <= C2.depth_to)
GROUP BY c1.row_id) AS B
ON A.row_id = B.row_id
GROUP BY A.colour, B.next_depth

--
David Portas
------------
Please reply only to the newsgroup
--

[DHatheway]

Re: Request: Help creating a difficult view.

Is this what you have in mind?

create table foo
(ROW_ID int, /* my datatypes vary from yours for my convenience
*/
DEPTH_FROM int,
DEPTH_TO int,
COLOUR Char(10))
go
insert foo values (1,0,5,'blue')
insert foo values (2,5,8,'blue')
insert foo values (3,8,10,'red')
insert foo values (4,10,12,'green ')
insert foo values (5,12,16,'green ')
go
select min(depth_from) as depth_from, max(depth_to) as depth_to, colour
from foo
group by colour

depth_from depth_to colour
----------- ----------- ----------
0 8 blue
10 16 green
8 10 red

(3 row(s) affected)

You may want an ORDER BY clause, too. Order of rows returned with GROUP BY
is not guaranteed/predictable.

"Dave Pylatuk" <davep@centurys ystems.net> wrote in message
news:pZgcb.4184 $1H3.311803@new s20.bellglobal. com...[color=blue]
> Hello all.
>
> I have a table defined in sql server as follows:
>
> ROW_ID (identity)
> DEPTH_FROM Number (8,3)
> DEPTH_TO Number (8,3)
> COLOUR Char(10)
>
> With typical data like:
> ROW_ID DEPTH_FROM DEPTH_TO COLOUR
> ---------------------------------------------------------------
> 1 0 5
> BLUE
> 2 5 8
> BLUE
> 3 8 10
> RED
> 4 10 12
> GREEN
> 5 12 16
> GREEN
>
> I want to create a view that will 'compress/roll up' the data so
> it appears like:
>
> DEPTH_FROM DEPTH_TO COLOUR
> ---------------------------------------------------------
> 0 8 BLUE
> 8 10 RED
> 10 16 GREEN
>
> I have been working on this for several days, with no luck,
> any help would be appreciated. BTW: there are no overlaps
> allowed in the depth_from, depth_to values.
>
> Thanks in advance.
>
>[/color]

[Tom Leylan]

Re: Request: Help creating a difficult view.

"Dave Pylatuk" <davep@centurys ystems.net> wrote...
[color=blue]
> I want to create a view that will 'compress/roll up' the data so
> it appears like:
>
> DEPTH_FROM DEPTH_TO COLOUR
> ---------------------------------------------------------
> 0 8 BLUE
> 8 10 RED
> 10 16 GREEN[/color]

I don't use SqlServer but... wouldn't this work?

select min(depth_from) , max(depth_to), colour from <tablename> group by
colour

[Dave Pylatuk]

Re: Request: Help creating a difficult view.

Testing these suggestions right now, thanks to all

"Dave Pylatuk" <davep@centurys ystems.net> wrote in message
news:pZgcb.4184 $1H3.311803@new s20.bellglobal. com...[color=blue]
> Hello all.
>
> I have a table defined in sql server as follows:
>
> ROW_ID (identity)
> DEPTH_FROM Number (8,3)
> DEPTH_TO Number (8,3)
> COLOUR Char(10)
>
> With typical data like:
> ROW_ID DEPTH_FROM DEPTH_TO COLOUR
> ---------------------------------------------------------------
> 1 0 5
> BLUE
> 2 5 8
> BLUE
> 3 8 10
> RED
> 4 10 12
> GREEN
> 5 12 16
> GREEN
>
> I want to create a view that will 'compress/roll up' the data so
> it appears like:
>
> DEPTH_FROM DEPTH_TO COLOUR
> ---------------------------------------------------------
> 0 8 BLUE
> 8 10 RED
> 10 16 GREEN
>
> I have been working on this for several days, with no luck,
> any help would be appreciated. BTW: there are no overlaps
> allowed in the depth_from, depth_to values.
>
> Thanks in advance.
>
>[/color]

[Shervin Shapourian]

Re: Request: Help creating a difficult view.

Hi Dave,

If there is no overlap but there can be gaps between intervals, this is the
query you want:

select DEPTH_FROM,
DEPTH_TO = (select min(DEPTH_TO)
from T T3
where DEPTH_TO not in (select DEPTH_FROM
from T T4
where T3.COLOUR = T4.COLOUR
and T3.DEPTH_FROM <>
T4.DEPTH_FROM
)
and T3.DEPTH_TO > T1.DEPTH_FROM
),
COLOUR
from T T1
where DEPTH_FROM not in (select DEPTH_TO
from T T2
where T1.COLOUR = T2.COLOUR
and T1.DEPTH_FROM <> T2.DEPTH_FROM
)
order by DEPTH_FROM

Good Luck,
Shervin



"Dave Pylatuk" <davep@centurys ystems.net> wrote in message
news:pZgcb.4184 $1H3.311803@new s20.bellglobal. com...[color=blue]
> Hello all.
>
> I have a table defined in sql server as follows:
>
> ROW_ID (identity)
> DEPTH_FROM Number (8,3)
> DEPTH_TO Number (8,3)
> COLOUR Char(10)
>
> With typical data like:
> ROW_ID DEPTH_FROM DEPTH_TO COLOUR
> ---------------------------------------------------------------
> 1 0 5
> BLUE
> 2 5 8
> BLUE
> 3 8 10
> RED
> 4 10 12
> GREEN
> 5 12 16
> GREEN
>
> I want to create a view that will 'compress/roll up' the data so
> it appears like:
>
> DEPTH_FROM DEPTH_TO COLOUR
> ---------------------------------------------------------
> 0 8 BLUE
> 8 10 RED
> 10 16 GREEN
>
> I have been working on this for several days, with no luck,
> any help would be appreciated. BTW: there are no overlaps
> allowed in the depth_from, depth_to values.
>
> Thanks in advance.
>
>[/color]

[John Gilson]

Re: Request: Help creating a difficult view.

"Dave Pylatuk" <davep@centurys ystems.net> wrote in message
news:pZgcb.4184 $1H3.311803@new s20.bellglobal. com...[color=blue]
> Hello all.
>
> I have a table defined in sql server as follows:
>
> ROW_ID (identity)
> DEPTH_FROM Number (8,3)
> DEPTH_TO Number (8,3)
> COLOUR Char(10)
>
> With typical data like:
> ROW_ID DEPTH_FROM DEPTH_TO COLOUR
> ---------------------------------------------------------------
> 1 0 5
> BLUE
> 2 5 8
> BLUE
> 3 8 10
> RED
> 4 10 12
> GREEN
> 5 12 16
> GREEN
>
> I want to create a view that will 'compress/roll up' the data so
> it appears like:
>
> DEPTH_FROM DEPTH_TO COLOUR
> ---------------------------------------------------------
> 0 8 BLUE
> 8 10 RED
> 10 16 GREEN
>
> I have been working on this for several days, with no luck,
> any help would be appreciated. BTW: there are no overlaps
> allowed in the depth_from, depth_to values.
>
> Thanks in advance.[/color]

This will also handle gaps between consecutive depth intervals.

CREATE TABLE ColorDepths
(
depth_from INT NOT NULL PRIMARY KEY,
depth_to INT NOT NULL,
color CHAR(10) NOT NULL,
CHECK (depth_from <= depth_to)
)

-- Your sample data augmented to better exercise code
INSERT INTO ColorDepths (depth_from, depth_to, color)
VALUES (0,5, 'BLUE')
INSERT INTO ColorDepths (depth_from, depth_to, color)
VALUES (5,8, 'BLUE')
INSERT INTO ColorDepths (depth_from, depth_to, color)
VALUES (8,10, 'RED')
INSERT INTO ColorDepths (depth_from, depth_to, color)
VALUES (11,12, 'GREEN')
INSERT INTO ColorDepths (depth_from, depth_to, color)
VALUES (12,15, 'GREEN')
INSERT INTO ColorDepths (depth_from, depth_to, color)
VALUES (16, 18, 'BLUE')
INSERT INTO ColorDepths (depth_from, depth_to, color)
VALUES (18, 24, 'BLUE')
INSERT INTO ColorDepths (depth_from, depth_to, color)
VALUES (26, 30, 'BLUE')

-- Associate consecutive depth intervals with natural numbers
CREATE VIEW OrderedColorDep ths (depth_from, depth_to, color, seq)
AS
SELECT D1.depth_from, D1.depth_to, D1.color, COUNT(*)
FROM ColorDepths AS D1
INNER JOIN
ColorDepths AS D2
ON D2.depth_from <= D1.depth_from
GROUP BY D1.depth_from, D1.depth_to, D1.color

-- Using above natural numbers, find endpoints
CREATE VIEW ColorDepthEnds (color, seq)
AS
SELECT OD1.color, OD1.seq
FROM OrderedColorDep ths AS OD1
LEFT OUTER JOIN
OrderedColorDep ths AS OD2
ON OD2.seq = OD1.seq + 1
WHERE OD2.color <> OD1.color OR -- consecutive depths w/ diff. colors
OD2.color IS NULL OR -- last (greatest) depth
OD2.depth_from > OD1.depth_to -- gap between consecutive depths

SELECT color,
MIN(depth_from) AS depth_from , MAX(depth_to) AS depth_to
FROM (SELECT OD.color, OD.depth_from, OD.depth_to,
MIN(DE.seq) AS seq
FROM OrderedColorDep ths AS OD
INNER JOIN
ColorDepthEnds AS DE
ON DE.seq >= OD.seq AND
DE.color = OD.color
GROUP BY OD.depth_from, OD.depth_to, OD.color) AS R
GROUP BY seq, color
ORDER BY depth_from

color depth_from depth_to
BLUE 0 8
RED 8 10
GREEN 11 15
BLUE 16 24
BLUE 26 30

Regards,
jag