I have a table with the following columns:
A B C
---------
1 10 X
1 11 X
2 15 X
3 20 Y
4 15 Y
4 20 Y
I want to group the data based on the B and C columns and count the distinct values of the A column. But if there are two ore more rows where the value on the A column is the same I want to get the maximum value from the B column.
If I do a simple group by the result would be:
B C Count
--------------
10 X 1
11 X 1
15 X 1
20 Y 2
15 Y 1
What I want is this result:
B C Count
--------------
11 X 1
15 X 1
20 Y 2
Is there any query that can return this result. Server is SQL Server 2005.
I like to work in steps: first get rid of duplicate A records, then group. Not the most efficient, but it works on your example.
with t1 as (
select A, max(B) as B, C
from YourTable
group by A, C
)
select count(A) as CountA, B, C
from t1
group by B, C
I have actually tested this:
SELECT
MAX( B ) AS B,
C,
Count
FROM
(
SELECT
B, C, COUNT(DISTINCT A) AS Count
FROM
t
GROUP BY
B, C
) X
GROUP BY C, Count
and it gives me:
B C Count
---- ---- --------
15 X 1
15 y 1
20 y 2
WITH cteA AS
(
SELECT
A, C,
MAX(B) OVER(PARTITION BY A, C) [Max]
FROM T1
)
SELECT
[Max] AS B, C,
COUNT(DISTINCT A) AS [Count]
FROM cteA
GROUP BY C, [Max];
Check this out. This should work in Oracle, although I haven't tested it;
select count(a), BB, CC from
(
select a, max(B) BB, Max(C) CC
from yourtable
group by a
)
group by BB,CC
Related
I have been working on this for a long time now and cant get the answer.
I have a table with 4 columns. I need to return two of these columns, A and B.
However I need the data to be filtered by the first column A. A is not a primary key. How can I achieve this? If I can return all the columns its also ok, as long as the data is only filtered by column A.
A B C D
1 e f r
1 e f r
1 e k t
2 c f r
2 c f r
3 l f r
This should return
A B C D
1 e f r
2 c f r
3 l f r
Which query wil give me this result? Until now I have this but it does not work well:
SELECT DISTINCT A, B, FROM myTable WHERE C=f
You could use Row_Number() to rank the rows within each distinct A value, then get the first row of each.
SELECT
a, b, c, d
FROM
(SELECT
a, b, c, d,
Row_Number() OVER (PARTITION BY a ORDER BY b, c, d) rn
FROM
myTable) mt
WHERE
rn = 1
Try
SELECT A,B FROM myTable WHERE C='f' GROUP BY A,B
use this
with cte as
(
select * , row_Number() over (Partition by A order by A) as aa from myTable
)
select * from cte where aa = 1
I have table like below
id a b c
1 2 1 3
2 3 2 1
3 16 14 15
4 10 12 13
5 15 16 14
6 10 12 8
I need to "normalize" this table by sorting values in columns a, b, c - row by row and deduping them counting dups
Expected result
a b c dups
1 2 3 2
14 15 16 2
10 12 13 1
8 10 12 1
I do have solution but I don't see how to "scale" it easily to case when I have more than 3 columns to normalize. The first and last column as you can see below is not an issue. Stuff gets messy for columns in the middle when number of columns > 3
select a, b, c, count(1) as dups from (
select a1 as a, if(a != a1 and a != c1, a, if(b != a1 and b != c1, b, c)) as b, c1 as c
from (select a, b, c, least(a, b, c) as a1, greatest(a, b, c) as c1 from table)
) group by a, b, c
Can anyone suggest another approach?
Below example works for 4 columns and can be adjusted to any number of columns by adding extra STRING(x) to CONCAT() and extra line for REGEXP_EXRACT per each extra column.
SELECT a, b, c, d, COUNT(1) AS dups
FROM (
SELECT id,
REGEXP_EXTRACT(s + ',', r'(?U)^(?:.*,){0}(.*),') AS a,
REGEXP_EXTRACT(s + ',', r'(?U)^(?:.*,){1}(.*),') AS b,
REGEXP_EXTRACT(s + ',', r'(?U)^(?:.*,){2}(.*),') AS c,
REGEXP_EXTRACT(s + ',', r'(?U)^(?:.*,){3}(.*),') AS d
FROM (
SELECT id, GROUP_CONCAT(s) AS s FROM (
SELECT id, s,
INTEGER(s) AS e,
ROW_NUMBER() OVER(PARTITION BY id ORDER BY e) pos
FROM (
SELECT id,
SPLIT(CONCAT(STRING(a),',',STRING(b),',',STRING(c),',',STRING(d))) AS s
FROM table
) ORDER BY id, pos
) GROUP BY id
)
) GROUP BY a, b, c, d
I want to randomly shuffle the values for one single column of a table based on a groupby. E.g., I have two columns A and B. Now, I want to randomly shuffle column B based on a groupby on A.
For an example, suppose that there are three distinct values in A. Now for each distinct value of A, I want to shuffle the values in B, but just with values having the same A.
Example input:
A B C
-------------------
1 1 x
1 3 a
2 4 c
3 6 d
1 2 a
3 5 v
Example output:
A B C
------------------
1 3 x
1 2 a
2 4 c
3 6 d
1 1 a
3 5 v
In this case, for A=1 the values for B got shuffled. The same happened for A=2, but as there is only one row it stayed like it was. For A=3 by chance the values for B also stayed like they were. The values for column C stay as they are.
Maybe this can be solved by using window functions, but I am unsure how exactly.
As a side note: This should be achieved in Google's BigQuery.
Is this what you're after ? (you tagged with both Mysql and Oracle .. so I answer here using Oracle)
[edit] corrected based on confirmed logic [/edit]
with w_data as (
select 1 a, 1 b from dual union all
select 1 a, 3 b from dual union all
select 2 a, 4 b from dual union all
select 3 a, 6 b from dual union all
select 1 a, 2 b from dual union all
select 3 a, 5 b from dual
),
w_suba as (
select a, row_number() over (partition by a order by dbms_random.value) aid
from w_data
),
w_subb as (
select a, b, row_number() over (partition by a order by dbms_random.value) bid
from w_data
)
select sa.a, sb.b
from w_suba sa,
w_subb sb
where sa.aid = sb.bid
and sa.a = sb.a
/
A B
---------- ----------
1 3
1 1
1 2
2 4
3 6
3 5
6 rows selected.
SQL> /
A B
---------- ----------
1 3
1 1
1 2
2 4
3 5
3 6
6 rows selected.
SQL>
Logic breakdown:
1) w_data is just your sample data set ...
2) randomize column a (not really needed, you could just rownum this, and let b randomize ... but I do so love (over)using dbms_random :) heh )
3) randomize column b - (using partition by analytic creates "groups" .. order by random radomizes the items within each group)
4) join them ... using both the group (a) and the randomized id to find a random item within each group.
by doing the randomize this way you can ensure that you get the same # .. ie you start with one "3" .. you end with one "3" .. etc.
I feel below should work in BigQuery
SELECT
x.A as A, x.B as Old_B, x.c as C, y.B as New_B
FROM (
SELECT A, B, C,
ROW_NUMBER() OVER(PARTITION BY A ORDER BY B, C) as pos
FROM [your_table]
) as x
JOIN (
SELECT
A, B, ROW_NUMBER() OVER(PARTITION BY A ORDER BY rnd) as pos
FROM (
SELECT A, B, RAND() as rnd
FROM [your_table]
)
) as y
ON x.A = y.A AND x.pos = y.pos
My query
SELECT a, b, c
FROM table
WHERE
a > 0 AND a < 4 AND
b IN (
SELECT z FROM table2
WHERE x = y
)
produces the following output:
A B C
1 1 Car
1 1 Keyboard
1 2 Apple
1 3 Frog
2 1 Carrot
2 2 Parrot
3 1 Doll
what I want is the following output
A B C
1 1 Car
2 1 Carrot
3 1 Doll
So basically for every A, the lowest B and associated C (as well as other columns).
I tried various join types, group bys, but I am running out of ideas.
How can I accomplish this?
Use a Top N Apply
SELECT a, b, c
FROM table
CROSS APPLY (SELECT top 1 z
FROM table2
WHERE x = y
order by z ) t2
WHERE a > 0 AND a < 4 AND
Do a join on a subquery:
SELECT a, b, c
FROM table t1
INNER JOIN (SELECT a a2, MIN(b) b2 FROM table GROUP BY a) t2
ON t1.a = t2.a2 AND t1.b = t2.b2
WHERE
a > 0 AND a < 4 AND
b IN (
SELECT z FROM table2
WHERE x = y
)
I have a table which has 3 columns A, B, C
I want to do a query like this:
select A, Max(B), ( C in the row having max B ) from Table group by A.
is there a way to do such a query?
Test Data:
A B C
2 5 3
2 6 1
4 5 1
4 7 9
6 5 0
the expected result would be:
2 6 1
4 7 9
6 5 0
;WITH CTE AS
(
SELECT A,
B,
C,
RN = ROW_NUMBER() OVER(PARTITION BY A ORDER BY B DESC)
FROM YourTable
)
SELECT A, B, C
FROM CTE
WHERE RN = 1
Try this
select t.*
from table t
join (Select A,max(b) B from table group by A) c
on c.a=t.a
and c.b=a.b