Below is my table and from column B I want to get the value 3 in results.
A
B
1
1
2
Null
3
2
4
Null
5
3
6
Null
7
Null
8
Null
Case not working: it should return 10
A
B
1
1
2
Null
3
2
4
Null
5
3
6
Null
7
Null
8
10
Use a LIMIT query:
SELECT *
FROM yourTable
WHERE B IS NOT NULL
ORDER BY A DESC
LIMIT 1;
Do you want to get the value '3' because it is the largest in 'B' column?
If so, you can run the following query:
SELECT *
FROM Table
WHERE B IS NOT NULL
ORDER BY B DESC
LIMIT 1;
There is not much to go on in the question. However, assuming that you can order by the col A, the answer would be
SELECT * from table
where B is not NULL
Order by A DESC
Limit 1
If A is numeric, then the order by works fine and you get all 3 non null values from column B. Then Order by descending + limit 1 will ensure you get last value of B
You already received really good answers that should help you. I just want to add a futher propose that works fine if both A and B are numeric and they are always sorted like in your example, meaning the highest b entry always has the highest a value.
SELECT MAX(b) FROM tableB
WHERE b IS NOT NULL
HAVING MAX(a);
Related
If I have the following table
id a b c time
-----------------------------
0 1 4 "ca" 23
1 NULL NULL NULL 18
2 NULL 1 "pn" 13
3 6 NULL "ar" 27
4 1 2 NULL 24
I want to return all rows with at least one null and one non-null in columns a, b, and c. So I want to return:
id a b c time
-----------------------------
2 NULL 1 "pn" 13
3 6 NULL "ar" 27
4 1 2 NULL 24
I know I can write
select *
from table
where ((a is null and (b is not null or c is not null))
or (a is not null and (b is null or c is null)))
But what happens if I need to consider 4 columns or more? It becomes a mess. Note that the table could have 20 or more columns, of which I am only considering a small subset of columns for null/non-null analysis. Is there a concise way of doing this? Thanks
One method would be to unpivot your data, and COUNT the NULL and non-NULL values, and filter on that:
SELECT V.ID,
V.a,
V.b,
V.c,
V.time
FROM (VALUES(0,1,4,'"ca"',23),
(1,NULL,NULL,NULL,18),
(2,NULL,1,'"pn"',13),
(3,6,NULL,'"ar"',27),
(4,1,2,NULL,24))V(ID,a,b,c,time)
CROSS APPLY (SELECT COUNT(UP.V) AS NonNull,
COUNT(CASE WHEN UP.V IS NULL THEN 1 END) AS IsNull
FROM (VALUES(CONVERT(varchar(1),V.a)),
(CONVERT(varchar(1),V.b)),
(CONVERT(varchar(1),V.c)))UP(V))C
WHERE C.[IsNull] > 0
AND C.NonNull > 0;
I have a table tableA below
ID number Estimate Client
---- ------
1 3 8 A
1 NULL 10 Null
1 5 11 A
1 NULL 19 Null
2 NULL 20 Null
2 2 70 A
.......
I would like to select previous row of Estimate column when number column is not null. For instance, when number = 3, then pre_estimate = NULL, when number = 5, then pre_estimate = 10, and when number = 2, then pre_estimate = 20.
The query below does not seem to return the correct answer in Hive. What should be correct way to do it?
select lag(Estimate, 1) OVER (partition by ID) as prev_estimate
from tableA
where number is not null
Consider the table with following structure:
number - int
estimate - int
order_column - int
order_column is taken as a column on which you want to sort your table rows.
Data in table:
number estimate order_column
3 8 1
NULL 10 2
5 11 3
NULL 19 4
NULL 20 5
2 70 6
I used the following query and got the result you have mentioned.
SELECT * FROM (SELECT number, estimate, lag(estimate,1) over(order by order_column) as prev_estimate from tableA) tbl where tbl.number is not null;
As per my understanding, I didn't find the reason to partition by id, that's why I haven't considered ID in the table.
The reason you were getting wrong results is due to the reason that where clause in main query will select only the records with number as not null and then it computes lag function, but you need to consider all the rows when computing the lag function and then you should select rows with number as not null.
I have table A:
id
1
2
3
4
5
and table B:
id
2
3
4
I left join A and B:
id id
1 NULL
2 2
3 3
4 4
5 NULL
And how can I get a new column like this:
id id flag
1 NULL 0
2 2 1
3 3 1
4 4 1
5 NULL 0
Generally speaking, I want all rows in A but not in B to be flaged as 0 and want all rows in both tables to be flaged as 1. How can I achieve that? Better not use CTE.
This is just a CASE expression:
CASE WHEN B.id IS NULL THEN 0 ELSE 1 END AS flag
Alternatively, you could use an IIF (which is shorthand CASE expression):
IIF(b.id IS NULL, 0,1)
I would recommend using exists:
select a.*,
(case when exists (select 1 from b where b.id = a.id
then 1 else 0
end) as flag
from a;
The purpose of using exists instead of left join is that you are guaranteed to not get duplicate rows -- even if ids are duplicated in b. That is a nice guarantee.
From a performance perspective, the two should be similar, but it is possible that the case is an iota faster.
Here is the data, call it table T
A B
-- --
1 14
2 15
3 16
4 1
4 3
4 6
4 9
4 12
4 15
I would like to get the value of A that has only one value and a B value of 15.
There are two rows where B=15 but there are 6 rows where A=4 and only one row where A=2.
So the correct SQL should return me the 2.
I have tried this but it returns both rows.
select A from T group by A,B having Count(A) = 1 and B = 15
This similarly fails:
select A from T where B = 15 group by A having count( A ) = 1
Try this:
select A
from T
group by A
having Count(A) = 1 and Max(B) = 15;
Your problem seems to be that you are grouping by both columns. You only want to group by A.
Admittedly, your query has group by A, T, but I think that is a typo, based on the described behavior.
You can check the count of B after grouping by A.
select A
from T
group by A
having Count(B) = 1 and max(B) = 15
still not found the solution described in update 2
thx for help
ill try to explain my issue with my poor english. hope someone can solve my problem.
i got the following table
A B
1 Y
2 null
3 Y
what result i want?
in dependency of the rank in column A i want to combine column B.
the result in that example is ... no result
the reason is because there is a null in rank 2 and the next and the last rank (=3) has a value (=Y).
next example
A B
1 Y
2 null
3 null
result i want is
A B
1 Y
because the way after is free... means 2 and the last 3 has null
another example
A B
1 null
2 N
3 null
again no result is what i want in this case. because first =1 has null value.
i try now to conclude ... if n(e.g. 2) of column B has value Y or N then the elements bevor (in this 1) must have the value Y or N.
thank you very much. i tried different technics without any success...
UPDATE 1
thank you fast comment
some example dates with expected result
example 1
A B
1 Y
2 N
3 null
4 null
expected result
A B
2 N
example 2
A B
1 N
2 Y
3 N
4 null
expected result
A B
3 N
example 3
A B
1 null
2 Y
3 Y
4 null
expected result
no result
example 4
A B
1 Y
2 Y
3 null
4 Y
expected result
no result
UPDATE 2
forget the basic case
A B
1 Y
2 N
3 Y
expected result
A B
3 N
Establish the highest value of A where B is Y or N, and the lowest value of A where B is null. Provided the first value is lower than the second value you have a valid result set.
select yt.A
, yt.B
from
( select max(case when B is not null then A else null end) as max_b_yn
, min(case when B is null then A else null end) as min_b_null
from your_table ) t1
, your_table yt
where ( t1.min_b_null is null
or t1.max_b_yn < t1.min_b_null )
and yt.A = t1.max_b_yn
/
I think you want the last row before the first NULL. If this is correct, then the following gets what you want:
select t.*
from t join
(select min(A) as NullA from t where B is NULL) t2
on t.A = t2.NullA - 1
Ah, I see. To get the last row with an "N":
select t.*
from t
where t.A in (select max(A) as MaxA
from t join
(select min(A) as NullA from t where B is NULL) t2
on t.A < t2.NullA
where t.B = 'N'
)
OK, I think I have what you need. It grabs the last row that has a value in column B as long as there isn't a row with a NULL that precedes it.
select MAX(A), B
from table_a
where B IS NOT NULL
and table_a.A > (
select MIN(A)
FROM table_a
WHERE B IS NULL
)
Group by B
select top 1 A, B
from #Temp
where B is not null
order by A desc
or
select top 1 A, B
from #Temp
where B = 'N'
order by A desc