Select distinct values from 1 column

Question

I want to select distinct values from only one column (the BoekingPlaatsId column) with this query:

SELECT MAX(BoekingPlaatsId), BewonerId, Naam, VoorNaam
F         


        

Answer 1

I think what you're looking for is something like this:

select distinct column1 from table1 where column2 = (select distinct column2 from table1)

Answer 2

I don't do alot of this so i'm not 100% certain of the syntax so you may need to tweak it slightly, google rank over and partition. Try this...

SELECT 
    *,
    RANK() OVER(PARTITION BY Naam  order by Naam ) as Rank
FROM
    TABLE
WHERE 
    Rank = 1

This is overkill for a 4 column table, but if you have a fairly denormalised table with alot of columns, this approach is invaluable for select distinct on 1 column.

Answer 3

This is how you can select from a table with only unique values for your column:

CREATE VIEW [yourSchema].[v_ViewOfYourTable] AS
WITH DistinctBoekingPlaats AS
(
    SELECT [BewonerId], 
           [Naam],
           [VoorNaam],
           [BoekingPlaatsId],
           ROW_NUMBER() OVER(PARTITION BY [BoekingPlaatsId] ORDER BY DESC) AS 'RowNum'
    FROM [yourSchema].[v_ViewOfYourTable]
)
SELECT * 
FROM DistinctProfileNames
WHERE RowNum = 1
--if you would like to apply group by you can do it in this bottom select clause but you don't need it to gather distinct values 

You don't need group by to accomplish this.

Answer 4

select Naam, Voornaam, min(BewonerId), min(BoekingPlaatsId) from tableName
group by Naam, Voornaam

Answer 5

I think you should be able to use

SELECT DISTINCT BewonerId, Naam, VoorNaam

You can't add BoekingPlaatsId, because:

• DISTINCT looks for unique rows
• You need to specify what BoekingPlaatsId value you want
  (In case of Jan Janssens, do you want BoekingPlaatsId 1 or 2?)

What also works is this:

SELECT MAX(BoekingPlaatsId), BewonerId, Naam, VoorNaam
FROM ...
GROUP BY BewonerId, Naam, VoorNaam

Answer 6

just group By those 2 columns

  Select Min(BoekingPlaatsId), Min(bewonerId), naam, voornaam
  from table
  group By naam, voornaam