CODEWITHSUNDEEP
sqlsql-servergroup-byaggregate
mushtaqck
mushtaqck

Reputation: 77

SQL Check if ungroup column values match

I have a sql table with following values

       |  col1 | col2|   source |  values
       |  1    |  2  |  A       |   null
       |  1    |  2  |  B       |   1.0
       |  1    |  2  |  C       |   null
       |  1    |  4  |  A       |   2.0
       |  1    |  4  |  B       |   2.0
       |  1    |  4  |  C       |   2.0
       |  1    |  5  |  A       |   null
       |  1    |  5  |  B       |   null
       |  1    |  5  |  C       |   null

How can I get an output with a group by of col1 and col2 with a flag:

Output:

       |  col1 | col2|   flag
       |  1    |  2  |   3
       |  1    |  4  |   1
       |  1    |  5  |   2

Upvotes: 2

Views: 765

Answers (3)

Agnius Vasiliauskas
Agnius Vasiliauskas

Reputation: 11277

...And solution without CTE if you want more portable SQL:

select col1,
       col2,
        case 
            when DistinctValuesWithoutNulls = 1 and NullCount = 0 then 1 
            when DistinctValuesWithoutNulls = 0 then 2
            when NullCount > 0 then 3
        end flag
from
(
    select  col1, 
            col2, 
            count(distinct [values]) DistinctValuesWithoutNulls, 
            sum(case when [values] is null then 1 else 0 end) NullCount
    from Table1
    group by col1, col2
) tmp

Upvotes: 2

Oleksandr Fedorenko
Oleksandr Fedorenko

Reputation: 16904

In SQLServer2005+

;WITH cte AS
 (
  SELECT col1, col2, [values],       
         COUNT(CASE WHEN [values] IS NULL THEN 1 END) OVER(PARTITION BY col1, col2) AS cntNULL,
         COUNT(*) OVER(PARTITION BY col1, col2) AS cntCol
  FROM dbo.test5
  )
  SELECT col1, col2, MAX(CASE WHEN cntNULL = 0 THEN 1
                              WHEN cntNULL = cntCol THEN 2
                              ELSE 3 END) AS flag
  FROM cte
  GROUP BY col1, col2

Demo on SQLFiddle

Upvotes: 3

Mahmoud Gamal
Mahmoud Gamal

Reputation: 79969

Or: based on your updated question:

  SELECT 
    col1, 
    col2,
    SUM(CASE WHEN SomeConditionHere THEN 1 ELSE 0 END) AS Flag
  FROM Table1
  GROUP BY col1, col2;

SQL Fiddle Demo

This will give you:

| COL1 | COL2 | FLAG |
----------------------
|    1 |    2 |    2 |
|    1 |    4 |    0 |
|    1 |    5 |    3 |

Note that: I assumed that the flag is how many NULL values are in the VALUES column, so I used "Values" IS NULL instead of SomeConditionHere.

I couldn't understand how the flag should be computed in the expected results you posted. You have to use the predicate that define your flag instead of "Values" IS NULL.

Update:

Try this:

WITH Flags
AS
(
  SELECT 
    col1, col2,
    COUNT(*) ValuesCount,
    SUM(CASE WHEN "Values" IS NULL THEN 1 ELSE 0 END) AS NULLValues
  FROM Table1 
  GROUP BY col1, col2
)
SELECT 
  col1,
  col2,
  Flag = CASE WHEN ValuesCount = NULLValues THEN 2
              WHEN NULLVALUES = 0 
               AND ValuesCount = (SELECT COUNT(*) 
                                  FROM Table1 t2
                                  WHERE t1.col1 = t2.col1
                                    AND t1.col2 = t2.col2) THEN 1
               ELSE 3
END
FROM Flags t1;

Updated SQL Fiddle Demo

This will give you:

| COL1 | COL2 | FLAG |
----------------------
|    1 |    2 |    3 |
|    1 |    4 |    1 |
|    1 |    5 |    2 |

Upvotes: 3

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