Reputation: 839
I have the following table that I want to group by type. When there are multiple rows with the same type (e.g., A & B type), I want to preserve the 'value' from the row with the highest rank (i.e., primary > secondary > tertiary..)
rowid | type | rank | value
1 | A | primary | 1
2 | A | secondary | 2
3 | B | secondary | 3
4 | B | tertiary | 4
5 | C | primary | 5
So the resulting table should look like
rowid | type | rank | value
1 | A | primary | 1
3 | B | secondary | 3
5 | C | primary | 5
Any suggestions will be highly appreciated!
p.s., I'm working in MS SQL Server.
Upvotes: 1
Views: 938
Reputation: 5110
Another way of doing is with Row_Number
and an Order By
specifying your rule with CASE
.
Schema:
CREATE TABLE #TAB(rowid INT, [type] VARCHAR(1), rankS VARCHAR(50) , value INT)
INSERT INTO #TAB
SELECT 1 , 'A' , 'primary' , 1
UNION ALL
SELECT 2 , 'A' , 'secondary', 2
UNION ALL
SELECT 3 , 'B' , 'secondary' , 3
UNION ALL
SELECT 4 , 'B' , 'tertiary' , 4
UNION ALL
SELECT 5 , 'C' , 'primary' , 5
Now apply rank rule with Row_Number
SELECT * FROM (
SELECT ROW_NUMBER() OVER(PARTITION BY [type] ORDER BY (CASE rankS
WHEN 'primary' THEN 1
WHEN 'secondary' THEN 2
WHEN 'tertiary' THEN 3 END )) AS SNO, * FROM #TAB
)A
WHERE SNO =1
Result:
+-----+-------+------+-----------+-------+
| SNO | rowid | type | rankS | value |
+-----+-------+------+-----------+-------+
| 1 | 1 | A | primary | 1 |
| 1 | 3 | B | secondary | 3 |
| 1 | 5 | C | primary | 5 |
+-----+-------+------+-----------+-------+
Upvotes: 1
Reputation: 5094
try this,
;WITH CTE
AS (
SELECT *
,row_number() OVER (
PARTITION BY [type] ORDER BY value
) rn
FROM @t
)
SELECT *
FROM cte
WHERE rn = 1
Upvotes: 1
Reputation: 1271241
You can use row_number()
. Here is a simple'ish method:
select t.*
from (select t.*,
row_number() over (partition by type
order by charindex(rank, 'primary,secondary,tertiary')
) as seqnum
from t
) t
where seqnum = 1;
This uses charindex()
as a simple method of ordering the ranks.
Upvotes: 4