Selecting and sorting data from a single table - sql

Question

Correction to my question....
I'm trying to select and sort in a query from a single table. The primary key for the table is a combination of a serialized number and a time/date stamp.
The table's name in the database is "A12", the columns are defined as:
Serial2D (PK, char(25), not null)
Completed (PK, datetime, not null)
Result (smallint, null)
MachineID (FK, smallint, null)
PT_1 (float, null)
PT_2 (float, null)
PT_3 (float, null)
PT_4 (float, null)
Since the primary key for the table is a combination of the "Serial2D" and "Completed", there can be multiple "Serial2D" entries with different values in the "Completed" and "Result" columns. (I did not make this database... I have to work with what I got)
I want to write a query that will utilize the value of the "Result" column ( always a "0" or "1") and retrive only unique rows for each "Serial2D" value. If the "Result" column has a "1" for that row, I want to choose it over any entries with that Serial that has a "0" in the Result column. There should be only one entry in the table that has a Result column entry of "1" for any Serial2D value.
Ex. table
Serial2d Completed Result PT_1 PT_2 PT_3 PT_4
------- ------- ------ ---- ---- ---- ----
A1 1:00AM 0 32.5 20 26 29
A1 1:02AM 0 32.5 10 29 40
A1 1:03AM 1 10 5 4 3
B1 1:04AM 0 29 4 1 9
B1 1:05AM 0 40 3 4 9
C1 1:06AM 1 9 7 6 4
I would like to be able to retrieve would be:
Serial2d Completed Result PT_1 PT_2 PT_3 PT_4
------- ------- ------ ---- ---- ---- ----
A1 1:03AM 1 10 5 4 3
B1 1:05AM 0 40 3 4 9
C1 1:06AM 1 9 7 6 4
I'm new to SQL and I'm still learning ALL the syntax. I'm finding it difficult to search for the correct operators to use since I'm not sure what I need, so please forgive my ignorance. A post with my answer could be staring me right in the face and i wouldn't know it, please just point me to it.
I appreciate the answers to my previous post, but the answers weren't sufficient for me due to MY lack of information and ineptness with SQL. I know this is probably insanely easy for some, but try to remember when you first started SQL... that's where I'm at.

Answer 1

Since you are using SQL Server, you can use Windowing Functions to get this data.
Using a sub-query:
select *
from
(
select *,
row_number() over(partition by serial2d
order by result desc, completed desc) rn
from a12
) x
where rn = 1
See SQL Fiddle with Demo
Or you can use CTE for this query:
;with cte as
(
select *,
row_number() over(partition by serial2d
order by result desc, completed desc) rn
from a12
)
select *
from cte c
where rn = 1;
See SQL Fiddle With Demo

Answer 2

You can group by Serial to get the MAX of each Time.
SELECT Serial, MAX([Time]) AS [Time]
FROM myTable
GROUP BY Serial
HAVING MAX(Result) => 0

Answer 3

SELECT
t.Serial,
max_Result,
MAX([time]) AS max_time
FROM
myTable t inner join
(SELECT
Serial,
MAX([Result]) AS max_Result
FROM
myTable
GROUP BY
Serial) m on
t.serial = m.serial and
t.result = m.max_result
group by
t.serial,
max_Result

Answer 4

This can be solved using a correlated sub-query:
SELECT
T.serial,
T.[time],
0 AS result
FROM tablename T
WHERE
T.result = 1
OR
NOT EXISTS(
SELECT 1
FROM tablename
WHERE
serial = T.serial
AND (
[time] > T.[time]
OR
result = 1
)
)