I have data like
a-b where c = 1
a-b where c = 2
how to select 2 columns same table with different where clause
i have try
select (select a-b from t where c = 1),
(select a-b from t where c = 2)
from t
Thank u
Your code should work, but you can use conditional aggregation:
select max(case when c = 1 then a - b end),
max(case when c = 2 then a - b end)
from t;
Related
Imagine this data.
Id
Type
1
A
1
B
1
B
2
A
3
B
I want to select table and ad two columns turning it to this. How can i do it? (In teradata)
Id
Type
Id with both A+B
Id with only A
1
A
1
0
1
B
1
0
1
B
1
0
2
A
0
1
3
B
0
0
I'm not familiar with teradata but in standard SQL next query should be working:
SELECT
T.*,
CASE WHEN Cnt = 2 THEN 1 ELSE 0 END AS BOTH_TYPES_PRESENT,
CASE WHEN Cnt = 1 AND Type = 'A' THEN 1 ELSE 0 END AS ONLY_A_PRESENT
FROM T
LEFT JOIN (
SELECT Id, COUNT(DISTINCT Type) Cnt FROM T WHERE Type IN ('A', 'B') GROUP BY Id
) CNT ON T.Id = CNT.Id;
SQL online editor
I have two tables and need to get a count of all entries from table A that have two specific matches in table B. Table B has tables A's Id as a foreign key.
Table a
ID Name
1 Foo
2 Bar
3 John
4 Jane
Table b
aID Value
1 12
1 12
2 8
3 8
3 12
4 12
4 8
I now need a count of all names in table A that have both value 8 AND 12 in table B at least once.
SELECT COUNT(*) FROM a join b on a.id = b.aId where b.value = 8 and b.value = 12
gets me 0 results. The correct result should be 2 (John and Jane).
edit:
Obviously, #Larnu is correct and 8 will never be 12.
Also, I should have clarified that there can be two or more of a single value in table B for any table A id, but none of the other (e.g. 8 twice but no 12). I updated the table to reflect that.
You can use EXISTS and HAVING:
SELECT COUNT(*) FROM a
WHERE EXISTS(SELECT b.aID FROM b
WHERE a.ID = b.aID
GROUP BY b.aID
HAVING COUNT(*) = 2)
If you want specifically value = 8 or 12 then add AND b.value IN(8,12) to the inner query
A subquery to get the number of times 8 and 12 appear for each row will do the trick:
select count(id) from
(select id, sum(case when b.Value = 8 then 1 else 0 end) as ct8,
sum(case when b.Value = 12 then 1 else 0 end) as ct12
from a inner join b on a.id = b.aID
group by a.id) as t
where ct8 >= 1 and ct12 >=1
Fiddle
Joining is not the answer here. You need a WHERE clause that includes a correlated subquery that checks your condition using COUNT() or EXISTS(). One of the following should do.
SELECT COUNT(*) FROM A
WHERE (SELECT COUNT(*) FROM B WHERE B.aID = A.ID AND B.VALUE IN (8, 12)) = 2
SELECT COUNT(*) FROM A
WHERE EXISTS(SELECT * FROM B WHERE B.aID = A.ID AND B.VALUE = 8)
AND EXISTS(SELECT * FROM B WHERE B.aID = A.ID AND B.VALUE = 12)
I have SQL server data Table, like this:
ID
SYMPTOM1
SYMPTOM2
1
A
B
1
C
D
2
E
F
3
A
C
3
D
E
I'd like to obtain this:
ID
SYMPTOM1
SYMPTOM2
SYMPTOM3
SYMPTOM4
1
A
B
C
D
2
E
F
3
A
C
D
E
That should be an "easy" pivot, but I can't figure it out.
How could a SQL query be written?
*EDIT
Excuse me, I have neglected an important detail. The number of rows in the table is very large, some 500.000 so the IDs are very large.
You could do it as a self join - use row number to have another column that is either 1 or 2 (depending on how many times ID appeared), 1 should always appear, 2 sometimes appears, so left joining those rows with 2 onto those rows with 1 (based on the id) gives you the end result..
WITH x AS(
SELECT
t.ID,
t.SYMPTOM1,
t.SYMPTOM2,
ROW_NUMBER() OVER (PARTITION BY t.ID ORDER BY t.SYMPTOM1) as rn
FROM t
)
SELECT
*
FROM
x x1
LEFT JOIN x x2 ON x1.id = x2.id AND x1.rn = 1 AND x2.rn = 2
You can pivot on a row-number
SELECT
t.ID,
SYMPTOM1 = MAX(CASE WHEN t.rn = 1 THEN t.SYMPTOM1 END),
SYMPTOM2 = MAX(CASE WHEN t.rn = 1 THEN t.SYMPTOM2 END),
SYMPTOM3 = MAX(CASE WHEN t.rn = 2 THEN t.SYMPTOM1 END),
SYMPTOM4 = MAX(CASE WHEN t.rn = 2 THEN t.SYMPTOM2 END)
FROM (
SELECT
t.*,
rn = ROW_NUMBER() OVER (PARTITION BY t.ID ORDER BY (SELECT 1))
FROM YourTable t
) t
GROUP BY t.ID;
I have a query for a multidimensional table using conditional aggregation
select A,
SUM(case when D = 3 then D end) as SUM_D1,
SUM(case when D = 4 then D end) as SUM_D2)
The result:
A SUM_D1 SUM_D2
-------------------
a1 100 NULL
a1 200 NULL
a3 NULL NULL
a4 NULL NULL
However, I would like to hide all NULL rows and columns as follows:
A SUM_D1
-----------
a1 100
a1 200
I have looked for similar problems but they are not my expected answer.
Any help is much appreciated,
Thank you
I think this does what you want:
select A,
coalesce(sum(case when D = 3 then D end),
sum(case when D = 4 then D end)
) as sum_d
from t
group by A
having sum(case when d in (3, 4) then 1 else 0 end) > 0;
Note that this returns only one column -- as in your example. If both "3" and "4" are in the data, then the value is for the "3"s.
If you want a query that returns a variable number of columns, then you need to use dynamic SQL -- or some other method. SQL queries return a fixed number of columns.
One method would be to return the values as an array:
select a,
array_agg(d order by d) as ds,
array_agg(sumd order by d) as sumds
from (select a, d, sum(d) as sumd
from t
where d in (3, 4)
group by a, d
) d
group by a;
To filter all-NULL rows you can use HAVING
select *
from
(
select A,
SUM(case when D = 3 then D end) as SUM_D1,
SUM(case when D = 4 then D end) as SUM_D2)
...
) as dt
where SUM_D1 is not null
and SUM_D2 is not null
Of course, if you got simple conditions like the ones in your example you better filter before aggregation:
select A,
SUM(case when D = 3 then D end) as SUM_D1,
SUM(case when D = 4 then D end) as SUM_D2)
...
where D in (3,4)
Now at least one calculation will return a value, thus no need to check for all-NULL.
To filter all-NULL columns you need some Dynamic SQL:
materialize the data in a temporary tabke using Insert/Select
scan each column for all-NULL select 1 from temp having count(SUM_D1) > 0
dynamically create the Select list based on this
run the Select
But why do you think you need this? It will be confusing for a user to run the same Stored Procedure and receive a different number of columns for each run.
I may have misinterpreted your question because the solution seems so simple:
select A,
SUM(case when D = 3 then D end) as SUM_D1,
SUM(case when D = 4 then D end) as SUM_D2)
where D is not null
This is not what you want, is it? :-)
Null appear because the condition that's not handled by case statement
select A,
SUM(case when D = 3 then D end) as SUM_D1,
SUM(case when D = 4 then D end) as SUM_D2
from
Table1
group by
A
having
(case when D = 3 or D = 4 then D end) is not null
As comment said if you want to suppress the null value.. You can use having to suppress null using is not null
I have two tables. Table A has an id column. Table B has an Aid column and a type column. Example data:
A: id
--
1
2
B: Aid | type
----+-----
1 | 1
1 | 1
1 | 3
1 | 1
1 | 4
1 | 5
1 | 4
2 | 2
2 | 4
2 | 3
I want to get all the IDs from table A where there is a certain amount of type 1 and type 3 actions. My query looks like this:
SELECT id
FROM A
WHERE (SELECT COUNT(type)
FROM B
WHERE B.Aid = A.id
AND B.type = 1) = 3
AND (SELECT COUNT(type)
FROM B
WHERE B.Aid = A.id
AND B.type = 3) = 1
so on the data above, just the id 1 should be returned.
Can I combine the 2 subqueries somehow? The goal is to make the query run faster.
Does postgres support CTEs?
WITH counts (Counts, Type, Aid) as (
select count(type), type
from b group by Type, Aid
)
select id
from A
join Counts B1 on b1.Aid = a.id and b1.type = 1
join Counts B3 on b3.Aid = a.id and b3.type = 3
where
b1.counts = 3 and b3.counts = 1
I'd suggest comparing the execution plans, but I suspect it would be similar since everything should get collapsed before execution.
Select ...
From A
Join (
Select B.Id
, Sum ( Case When B.Type = 1 Then 1 Else 0 End ) As Type1Count
, Sum ( Case When B.Type = 3 Then 1 Else 0 End ) As Type3Count
From B
Where B.Type In(1,3)
Group By B.Id
) As Z
On Z.Id = A.Id
Where Z.Type1Count = 3
And Z.Type3Count = 1
This works in TSQL, does it work in Postgres?
SELECT A.ID
FROM A
WHERE A.ID in
(
SELECT AID
FROM B
GROUP BY AID
HAVING
SUM(CASE WHEN Type = 1 THEN 1 ELSE 0 END) = 3
OR SUM(CASE WHEN Type = 3 THEN 1 ELSE 0 END) = 1
)
Another alternative:
SELECT DISTINCT Aid FROM (
SELECT Aid,type,count(*) as n from B
GROUP BY Aid,type, ) as g
WHERE ( g.n=1 AND g.type = 3 )
OR ( g.n=3 AND g.type = 1 )
I doubt this will perform better than your original, though.
You seem to be doing the best strategy: counting only the candidate rows.
Perhaps some redundant prefiltering might help:
SELECT DISTINCT Aid FROM (
SELECT Aid,type,count(*) as n from B
WHERE g.type = 3 OR g.type = 1 -- prefilter
GROUP BY Aid,type, ) as g
WHERE ( g.n=1 AND g.type = 3 )
OR ( g.n=3 AND g.type = 1 )