I have data in the below format
g_name amt flag
g1 0 0
g1 0 0
g1 10 1
g1 0 0
g1 15 2
g1 0 0
and I would require in the below format
n1 will have data starting from row where amt hits 1 and it keeps retaining it till the end, similarly n2 will have data starting from row where amt hits 2 and it keeps retaining it till the end, please help me with any window functions with out needing joins. please.
g_name amt flag n1 n2
g1 0 0 0 0
g1 0 0 0 0
g1 10 1 10 0
g1 0 0 10 0
g1 15 2 10 15
g1 0 0 10 15
I added a column for ordering - change as needed. I also added a few more rows with a different g_name, presumably this must be done "by g_name".
This is a good test case for the first_value() analytic function. It has the ability to ignore nulls - so we make the amt NULL when flag is not 1 (or 2, etc.) and then apply first_value() with the proper PARTITION BY and ORDER BY clauses.
with
test_data ( id, g_name, amt, flag ) as (
select 1, 'g1', 0, 0 from dual union all
select 2, 'g1', 0, 0 from dual union all
select 3, 'g1', 10, 1 from dual union all
select 4, 'g1', 0, 0 from dual union all
select 5, 'g1', 15, 2 from dual union all
select 6, 'g1', 0, 0 from dual union all
select 1, 'g2', 0, 0 from dual union all
select 2, 'g2', 4, 1 from dual union all
select 3, 'g2', 3, 2 from dual union all
select 4, 'g2', 0, 0 from dual
)
-- end of test data; solution (SQL query) begins below this line
select id, g_name, amt, flag,
coalesce (first_value(case when flag = 1 then amt end ignore nulls)
over (partition by g_name order by id), 0) as n1,
coalesce (first_value(case when flag = 2 then amt end ignore nulls)
over (partition by g_name order by id), 0) as n2
from test_data
order by g_name, id
;
ID G_NAME AMT FLAG N1 N2
--- ------ ---------- ---------- ---------- ----------
1 g1 0 0 0 0
2 g1 0 0 0 0
3 g1 10 1 10 0
4 g1 0 0 10 0
5 g1 15 2 10 15
6 g1 0 0 10 15
1 g2 0 0 0 0
2 g2 4 1 4 0
3 g2 3 2 4 3
4 g2 0 0 4 3
SQL tables represent unordered sets. There is no ordering, unless a column specifies that ordering. Let me assume that such a column exists.
If so, you can do this with analytic functions:
select t.*,
max(case when flag = 1 then amt else 0 end) over (order by ??) as n1,
max(case when flag = 2 then amt else 0 end) over (order by ??) as n2
from t;
The ?? specifies the ordering.
Related
I have a table for subjects as follows:
id Subject Grade Ext
100 Math 6 +
100 Science 4 -
100 Hist 3
100 Geo 2 +
100 CompSi 1
I am expecting output per student in a class(id = 100) as follows:
Grade Ext StudentGrade
6 + 1
6 0
6 - 0
5 + 0
5 0
5 - 0
4 + 0
4 0
4 - 1
3 + 0
3 1
3 - 0
2 + 1
2 0
2 - 0
1 + 0
1 1
1 - 0
I would want this done on oracle/sql rather than UI. Any inputs please.
You should generate rows first, before join them with your table like below. I use the with clause here to generate the 18 rows in your sample.
with rws (grade, ext) as (
select ceil(level/3), decode(mod(level, 3), 0, '+', 1, '-', null)
from dual
connect by level <= 3 * 6
)
select r.grade, r.ext, nvl2(t.Ext, 1, 0) studentGrade
from rws r
left join your_table t
on t.Grade = r.Grade and decode(t.Ext, r.Ext, 1, 0) = 1
order by 1 desc, decode(r.ext, null, 2, '-', 3, '+', 1)
You could do something like this. In the WITH clause I generate two small "helper" tables (really, inline views) for grades from 1 to 6 and for "extensions" of +, null and -. In the "extensions" view I also create an "ordering" column to use in ordering the final output (if you are wondering why I included that).
Also in the WITH clause I included sample data - you will have to remove that and instead use your actual table name in the main query.
The idea is to cross-join "grades" and "extensions", and left-outer-join the result to your input data. Count the grades from the input data, grouped by grade and extension, and after filtering the desired id. The decode thing in the join condition is needed because for extension we want to treat null as equal to null - something that decode does nicely.
with
sample_inputs (id, subject, grade, ext) as (
select 100, 'Math' , 6, '+' from dual union all
select 100, 'Science', 4, '-' from dual union all
select 100, 'Hist' , 3, null from dual union all
select 100, 'Geo' , 2, '+' from dual union all
select 100, 'CompSi' , 1, null from dual
)
, g (grade) as (select level from dual connect by level <= 6)
, e (ord, ext) as (
select 1, '+' from dual union all
select 2, null from dual union all
select 3, '-' from dual
)
select g.grade, e.ext, count(t.grade) as studentgrade
from g cross join e left outer join sample_inputs t
on t.grade = g.grade and decode(t.ext, e.ext, 0) = 0
and t.id = 100 -- change this as needed!
group by g.grade, e.ext, e.ord
order by g.grade desc, e.ord
;
OUTPUT:
GRADE EXT STUDENTGRADE
----- --- ------------
6 + 1
6 0
6 - 0
5 + 0
5 0
5 - 0
4 + 0
4 0
4 - 1
3 + 0
3 1
3 - 0
2 + 1
2 0
2 - 0
1 + 0
1 1
1 - 0
It looks like you want sparse data to be filled in as part of joining students and subjects.
Since Oracle 10g the correct way to do this has been with a "partition outer join".
The documentation has examples.
https://docs.oracle.com/en/database/oracle/oracle-database/21/sqlrf/SELECT.html#GUID-CFA006CA-6FF1-4972-821E-6996142A51C6
I've data like this.
ID IND
1 0
2 0
3 1
4 0
5 1
6 0
7 0
I want to count the zeros before the value 1. So that, the output will be like below.
ID IND OUT
1 0 0
2 0 0
3 1 2
4 0 0
5 1 1
6 0 0
7 0 2
Is it possible without pl/sql? I tried to find the differences between row numbers but couldn't achieve it.
The match_recognize clause, introduced in Oracle 12.1, can do quick work of such "row pattern recognition" problems. The solution is just a bit complex due to the special treatment of a "last row" with ID = 0, but it is straightforward otherwise.
As usual, the with clause is not part of the solution; I include it to test the query. Remove it and use your actual table and column names.
with
inputs (id, ind) as (
select 1, 0 from dual union all
select 2, 0 from dual union all
select 3, 1 from dual union all
select 4, 0 from dual union all
select 5, 1 from dual union all
select 6, 0 from dual union all
select 7, 0 from dual
)
select id, ind, out
from inputs
match_recognize(
order by id
measures case classifier() when 'Z' then 0
when 'O' then count(*) - 1
else count(*) end as out
all rows per match
pattern ( Z* ( O | X ) )
define Z as ind = 0, O as ind != 0
);
ID IND OUT
---------- ---------- ----------
1 0 0
2 0 0
3 1 2
4 0 0
5 1 1
6 0 0
7 0 2
You can treat this as a gaps-and-islands problem. You can define the "islands" by the number of "1"s one or after each row. Then use a window function:
select t.*,
(case when ind = 1 or row_number() over (order by id desc) = 1
then sum(1 - ind) over (partition by grp)
else 0
end) as num_zeros
from (select t.*,
sum(ind) over (order by id desc) as grp
from t
) t;
If id is sequential with no gaps, you can do this without a subquery:
select t.*,
(case when ind = 1 or row_number() over (order by id desc) = 1
then id - coalesce(lag(case when ind = 1 then id end ignore nulls) over (order by id), min(id) over () - 1)
else 0
end)
from t;
I would suggest removing the case conditions and just using the then clause for the expression, so the value is on all rows.
I have the data for student absence which I got after some transformations. The data is day by day:
WITH datasample AS (
SELECT 1 AS StudentID, 20180101 AS DateID, 0 AS AbsentToday, 0 AS AbsentYesterday UNION ALL
SELECT 1, 20180102, 1, 0 UNION ALL
SELECT 1, 20180103, 1, 1 UNION ALL
SELECT 1, 20180104, 1, 1 UNION ALL
SELECT 1, 20180105, 1, 1 UNION ALL
SELECT 1, 20180106, 0, 1 UNION ALL
SELECT 2, 20180101, 0, 0 UNION ALL
SELECT 2, 20180102, 1, 0 UNION ALL
SELECT 2, 20180103, 1, 1 UNION ALL
SELECT 2, 20180104, 0, 1 UNION ALL
SELECT 2, 20180105, 1, 0 UNION ALL
SELECT 2, 20180106, 1, 1 UNION ALL
SELECT 2, 20180107, 0, 1
)
SELECT *
FROM datasample
ORDER BY StudentID, DateID
I need to add a column (AbsencePeriodInMonth) which would calculate the student's absence period during the month.
For example, StudentID=1 was absent in one consecutive period during the month and StudentID=2 had two periods, something like this:
StudentID DateID AbsentToday AbsentYesterday AbsencePeriodInMonth
1 20180101 0 0 0
1 20180102 1 0 1
1 20180103 1 1 1
1 20180104 1 1 1
1 20180105 1 1 1
1 20180106 0 1 0
2 20180101 0 0 0
2 20180102 1 0 1
2 20180103 1 1 1
2 20180104 0 1 0
2 20180105 1 0 2
2 20180106 1 1 2
2 20180107 0 1 0
My goal is actually to calculate the consecutive absent days prior to each day in the fact table, I think I can do it if I get the AbsencePeriodInMonth column, by having this added to my query after the *:
,CASE WHEN AbsentToday = 1 THEN DENSE_RANK() OVER(PARTITION BY StudentID, AbsencePeriodInMonth ORDER BY DateID)
ELSE 0
END AS DaysAbsent
Any idea on how I can add that AbsencePeriodInMonth or maybe calculate the consecutive absent days in some other way?
You can identify each period by counting the number of 0s before hand. Then you can enumerate them using dense_rank().
select ds.*,
(case when absenttoday = 1 then dense_rank() over (partition by studentid order by grp)
else 0
end) as AbsencePeriodInMonth
from (select ds.*, sum(case when absenttoday = 0 then 1 else 0 end) over (partition by studentid order by dateid) as grp
from datasample ds
) ds
order by StudentID, DateID;
Here is a SQL Fiddle.
Using Recursive CTE and Dense_Rank
WITH datasample AS (
SELECT 1 AS StudentID, 20180101 AS DateID, 0 AS AbsentToday, 0 AS AbsentYesterday UNION ALL
SELECT 1, 20180102, 1, 0 UNION ALL
SELECT 1, 20180103, 1, 1 UNION ALL
SELECT 1, 20180104, 1, 1 UNION ALL
SELECT 1, 20180105, 1, 1 UNION ALL
SELECT 1, 20180106, 0, 1 UNION ALL
SELECT 2, 20180101, 0, 0 UNION ALL
SELECT 2, 20180102, 1, 0 UNION ALL
SELECT 2, 20180103, 1, 1 UNION ALL
SELECT 2, 20180104, 0, 1 UNION ALL
SELECT 2, 20180105, 1, 0 UNION ALL
SELECT 2, 20180106, 1, 1 UNION ALL
SELECT 2, 20180107, 0, 1
), cte as
(Select *,DateID as dd
from datasample
where AbsentToday = 1 and AbsentYesterday = 0
union all
Select d.*, c.dd
from datasample d
join cte c
on d.StudentID = c.StudentID and d.DateID = c.DateID + 1
where d.AbsentToday = 1
), cte1 as
(
Select *, DENSE_RANK() over (partition by StudentId order by dd) as de
from cte
)
Select d.*, IsNull(c.de,0) as AbsencePeriodInMonth
from cte1 c
right join datasample d
on d.StudentID = c.StudentID and c.DateID = d.DateID
order by d.StudentID, d.DateID
I have a table that looks like below:
ID|Date |X| Flag |
1 |1/1/16|2| 0
2 |1/1/16|0| 0
3 |1/1/16|0| 0
1 |2/1/16|0| 0
2 |2/1/16|1| 0
3 |2/1/16|2| 0
1 |3/1/16|2| 0
2 |3/1/16|1| 0
3 |3/1/16|2| 0
I'm trying to make it so that flag is populated if X=2 in the PREVIOUS month. As such, it should look like this:
ID|Date |X| Flag |
1 |1/1/16|2| 0
2 |1/1/16|0| 0
3 |1/1/16|0| 0
1 |2/1/16|2| 1
2 |2/1/16|1| 0
3 |2/1/16|2| 0
1 |3/1/16|2| 1
2 |3/1/16|1| 0
3 |3/1/16|2| 1
I use this in SQL:
`select ID, date, X, flag into Work_Table from t
(
Select ID, date, X, flag,
Lag(X) Over (Partition By ID Order By date Asc) As Prev into Flag_table
From Work_Table
)
Update [dbo].[Flag_table]
Set flag = 1
where prev = '2'
UPDATE t
Set t.flag = [dbo].[Flag_table].flag FROM T
JOIN [dbo].[Flag_table]
ON t.ID= [dbo].[Flag_table].ID where T.date = [dbo].[Flag_table].date`
However I cannot do this in Bigquery. Any ideas?
Below is for BigQuery Standard SQL
#standardSQL
SELECT id, dt, x,
IF(LAG(x = 2) OVER(PARTITION BY id ORDER BY dt), 1, 0) flag
FROM `project.dataset.work_table`
You can test / play with it using dummy data from your question as
#standardSQL
WITH `project.dataset.work_table` AS (
SELECT 1 id, '1/1/16' dt, 2 x, 0 flag UNION ALL
SELECT 2, '1/1/16', 0, 0 UNION ALL
SELECT 3, '1/1/16', 0, 0 UNION ALL
SELECT 1, '2/1/16', 0, 0 UNION ALL
SELECT 2, '2/1/16', 1, 0 UNION ALL
SELECT 3, '2/1/16', 2, 0 UNION ALL
SELECT 1, '3/1/16', 2, 0 UNION ALL
SELECT 2, '3/1/16', 1, 0 UNION ALL
SELECT 3, '3/1/16', 2, 0
)
SELECT id, dt, x,
IF(LAG(x = 2) OVER(PARTITION BY id ORDER BY dt), 1, 0) flag
FROM `project.dataset.work_table`
ORDER BY dt, id
with result as
Row id dt x flag
1 1 1/1/16 2 0
2 2 1/1/16 0 0
3 3 1/1/16 0 0
4 1 2/1/16 0 1
5 2 2/1/16 1 0
6 3 2/1/16 2 0
7 1 3/1/16 2 0
8 2 3/1/16 1 0
9 3 3/1/16 2 1
I have a table which looks like this ( 10 billion rows)
AID BID CID
1 2 1
1 6 9
0 1 4
1 3 2
1 100 2
0 4 2
0 0 1
The AID could only be 0 or 1. BID and CID could be anything.
Now I want to select events first with AID=1 and then AID=0, and again AID=1 and then AID=0.
The idea is to select equal numbers of AID=1 and AID=0 event.
How can I achieve that?
The expected result is
AID BID CID
1 2 1
0 1 4
1 6 9
0 4 2
1 3 2
0 0 1
;WITH cte AS (
select *
FROM (VALUES
(1, 2, 1),
(1, 6, 9),
(0, 1, 4),
(1, 3, 2),
(1, 100, 2),
(0, 4, 2),
(0, 0, 1)
) as t(AID, BID, CID)
),
withrow AS (
SELECT ROW_NUMBER() OVER (PARTITION BY AID ORDER BY AID) as RN, *
FROM cte)
SELECT AID,BID,CID
FROM withrow
ORDER BY RN asc , aid desc
Output:
AID BID CID
----------- ----------- -----------
1 100 2
0 4 2
1 3 2
0 1 4
1 6 9
0 0 1
1 2 1
(7 row(s) affected)