Comparing the length of two similar strings and picking the longest - sql-server

Question

I am Trying to compare two strings and pick the longest if they are similar, I have managed to pick the longest by using the following code:
SELECT D.RID, ProductID, Product, [Length] FROM (
SELECT RID, MAX([Length]) AS theLength FROM SortData GROUP BY RID)
AS X INNER JOIN SortData AS D ON D.RID = X.RID AND D.[Length] = X.theLength
But I am now trying to make sure that the code only pick the longest string if it is a like the word it is comparing it to, I have attempted the following code in a few ways but I would be grateful if somebody could help me:
SELECT D.RID, D.ProductID, Product, [Length] FROM (
SELECT RID, Product, MAX([Length]) AS theLength FROM SortData GROUP BY RID)
AS X INNER JOIN SortData AS D ON D.RID = X.RID AND D.[Length] = X.theLength WHERE
D.Product LIKE Product
Using this code I get the Following Error:
Msg 8120, Level 16, State 1, Line 3 Column 'SortData.Product' is
invalid in the select list because it is not contained in either an
aggregate function or the GROUP BY clause. Msg 209, Level 16, State 1,
Line 5 Ambiguous column name 'Product'. Msg 209, Level 16, State 1,
Line 2 Ambiguous column name 'Product'.
Example of the Data I would Like to pick:
1 Sam
1 Samantha
2 Oliver
3 Ollie
4 Benjamin
4 Ben
...
I would expect the output list to be like:
1 Samantha
2 Oliver
3 Ollie
4 Benjamin
...
To Clarify what I am trying to do in the context of this example, I am trying to compare the two Names and if the are LIKE (e.g. x.Name LIKE Name) then pick the longest...
As Requested here is further test data:
1 Hydrogen
1 Hydrogen Oxide
1 Carbon Monoxide
2 Carbon
2 Carbon
2 Carbon Dioxide
3 Carbon Monoxide
3 Carbon Dioxide
3 Oxygen
4 Hydrogen Dioxide
Desired Results are as so:
1 Hydrogen Oxide
1 Carbon Monoxide
2 Carbon Dioxide
3 Carbon Monoxide
3 Oxygen
4 Hydrogen Dioxide

Answer 1

Perhaps another option: The WITH TIES clause in concert with Row_Number()
Example
Select Top 1 with ties *
From YourTable
Order By Row_Number() over (Partition by ID Order By Len(Name) desc)

Answer 2

Your query doesn't come close to your sample data and output. So I built this around the sample data provided to demonstrate one way of solving this.
declare #Something table
(
Col1 int
, Col2 varchar(20)
)
insert #Something values
(1, 'Sam')
, (1, 'Samantha')
, (2, 'Oliver')
, (3, 'Ollie')
select x.Col1
, x.Col2
from
(
select *
, RowNum = ROW_NUMBER() over(partition by Col1 order by LEN(Col2) desc)
from #Something
) x
where x.RowNum = 1
---EDIT---
To demonstrate that this code still returns the desired output from your new sample data...
declare #Something table
(
Col1 int
, Col2 varchar(20)
)
insert #Something values
(1, 'Sam')
, (1, 'Samantha')
, (2, 'Oliver')
, (3, 'Ollie')
, (4, 'Benjamin')
, (4, 'Ben')
select x.Col1
, x.Col2
from
(
select *
, RowNum = ROW_NUMBER() over(partition by Col1 order by LEN(Col2) desc)
from #Something
) x
where x.RowNum = 1
This returns:
1 Samantha
2 Oliver
3 Ollie
4 Benjamin
Since you claim this still doesn't work you need to provide an example of how or why this doesn't work. You keep mentioning LIKE but have not explained or demonstrated how that comes into play here. Help me understand the problem and I can help you find a solution.

Answer 3

I Ended up figuring it out and using the following code:
SELECT D.RID, ProductID, D.Product, [Length] FROM
(
SELECT RID, MAX([Length]) AS theLength
FROM SortData GROUP BY RID
) AS X
INNER JOIN SortData AS D ON D.RID = X.RID AND D.[Length] = X.theLength
WHERE D.Product LIKE Product
GO