CODEWITHSUNDEEP
sql-servert-sql
mmcglynn
mmcglynn

Reputation: 7662

SELECT DISTINCT on one column

Using SQL Server, I have...

ID  SKU     PRODUCT
=======================
1   FOO-23  Orange
2   BAR-23  Orange
3   FOO-24  Apple
4   FOO-25  Orange

I want 

1   FOO-23  Orange
3   FOO-24  Apple

This query isn't getting me there. How can I SELECT DISTINCT on just one column?

SELECT 
[ID],[SKU],[PRODUCT]
FROM [TestData] 
WHERE ([PRODUCT] = 
(SELECT DISTINCT [PRODUCT] FROM [TestData] WHERE ([SKU] LIKE 'FOO-%')) 
ORDER BY [ID]

Upvotes: 341

Views: 672554

Answers (7)

Ivan
Ivan

Reputation: 4753

Here is a version, basically the same as a couple of the other answers, but that you can copy paste into your SQL server Management Studio to test, (and without generating any unwanted tables), thanks to some inline values.

WITH [TestData]([ID],[SKU],[PRODUCT]) AS
(
    SELECT *
    FROM (
        VALUES
        (1,   'FOO-23',  'Orange'),
        (2,   'BAR-23',  'Orange'),
        (3,   'FOO-24',  'Apple'),
        (4,   'FOO-25',  'Orange')
    )
    AS [TestData]([ID],[SKU],[PRODUCT])
)

SELECT * FROM [TestData] WHERE [ID] IN 
(
    SELECT MIN([ID]) 
    FROM [TestData] 
    GROUP BY [PRODUCT]
)

Result

ID  SKU     PRODUCT
1   FOO-23  Orange
3   FOO-24  Apple

I have ignored the following ...

WHERE ([SKU] LIKE 'FOO-%')

as its only part of the authors faulty code and not part of the question. It's unlikely to be helpful to people looking here.

Upvotes: 13

Anna Karthi
Anna Karthi

Reputation: 283

Try this:

SELECT * FROM [TestData] WHERE Id IN(SELECT DISTINCT MIN(Id) FROM [TestData] GROUP BY Product)   

Upvotes: 7

Bartosz X
Bartosz X

Reputation: 2798

I know it was asked over 6 years ago, but knowledge is still knowledge. This is different solution than all above, as I had to run it under SQL Server 2000:

DECLARE @TestData TABLE([ID] int, [SKU] char(6), [Product] varchar(15))
INSERT INTO @TestData values (1 ,'FOO-23', 'Orange')
INSERT INTO @TestData values (2 ,'BAR-23', 'Orange')
INSERT INTO @TestData values (3 ,'FOO-24', 'Apple')
INSERT INTO @TestData values (4 ,'FOO-25', 'Orange')

SELECT DISTINCT  [ID] = ( SELECT TOP 1 [ID]  FROM @TestData Y WHERE Y.[Product] = X.[Product])
                ,[SKU]= ( SELECT TOP 1 [SKU] FROM @TestData Y WHERE Y.[Product] = X.[Product])
                ,[PRODUCT] 
            FROM @TestData X

Upvotes: 11

Jakob Egger
Jakob Egger

Reputation: 12041

The simplest solution would be to use a subquery for finding the minimum ID matching your query. In the subquery you use GROUP BY instead of DISTINCT:

SELECT * FROM [TestData] WHERE [ID] IN (
   SELECT MIN([ID]) FROM [TestData]
   WHERE [SKU] LIKE 'FOO-%'
   GROUP BY [PRODUCT]
)

Upvotes: 60

KM.
KM.

Reputation: 103587

try this:

SELECT 
    t.*
    FROM TestData t
        INNER JOIN (SELECT
                        MIN(ID) as MinID
                        FROM TestData
                        WHERE SKU LIKE 'FOO-%'
                   ) dt ON t.ID=dt.MinID

EDIT
once the OP corrected his samle output (previously had only ONE result row, now has all shown), this is the correct query:

declare @TestData table (ID int, sku char(6), product varchar(15))
insert into @TestData values (1 ,  'FOO-23'      ,'Orange')
insert into @TestData values (2 ,  'BAR-23'      ,'Orange')
insert into @TestData values (3 ,  'FOO-24'      ,'Apple')
insert into @TestData values (4 ,  'FOO-25'      ,'Orange')

--basically the same as @Aaron Alton's answer:
SELECT
    dt.ID, dt.SKU, dt.Product
    FROM (SELECT
              ID, SKU, Product, ROW_NUMBER() OVER (PARTITION BY PRODUCT ORDER BY ID) AS RowID
              FROM @TestData
              WHERE  SKU LIKE 'FOO-%'
         ) AS dt
    WHERE dt.RowID=1
    ORDER BY dt.ID

Upvotes: 15

Lecko
Lecko

Reputation: 

SELECT min (id) AS 'ID', min(sku) AS 'SKU', Product
    FROM TestData
    WHERE sku LIKE 'FOO%' -- If you want only the sku that matchs with FOO%
    GROUP BY product 
    ORDER BY 'ID'

Upvotes: 10

Aaron Alton
Aaron Alton

Reputation: 23226

Assuming that you're on SQL Server 2005 or greater, you can use a CTE with ROW_NUMBER():

SELECT  *
FROM    (SELECT ID, SKU, Product,
                ROW_NUMBER() OVER (PARTITION BY PRODUCT ORDER BY ID) AS RowNumber
         FROM   MyTable
         WHERE  SKU LIKE 'FOO%') AS a
WHERE   a.RowNumber = 1

Upvotes: 395

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