I am working on a time attendance system. I have the employees' transactions stored in the following table:
I want to get the earliest and the latest transactions for each employee including their date and type.
I am able to get the dates using grouping and aggregation. However, I am not able to figure out how to get types with them.
Would you please help me in it.
Thank you.
That's what the FIRST and LAST aggregate functions are designed for.
Here is a link to the documentation:
FIRST: http://download.oracle.com/docs/cd/E11882_01/server.112/e17118/functions065.htm#SQLRF00641
LAST: http://download.oracle.com/docs/cd/E11882_01/server.112/e17118/functions083.htm#sthref1206
And here is an example:
SQL> create table my_transactions (id,employee_id,action_date,type)
2 as
3 select 1, 1, sysdate, 'A' from dual union all
4 select 2, 1, sysdate-1, 'B' from dual union all
5 select 3, 1, sysdate-2, 'C' from dual union all
6 select 4, 1, sysdate-3, 'D' from dual union all
7 select 5, 2, sysdate-11, 'E' from dual union all
8 select 6, 2, sysdate-12, 'F' from dual union all
9 select 7, 2, sysdate-13, 'G' from dual
10 /
Table created.
SQL> select *
2 from my_transactions
3 order by id
4 /
ID EMPLOYEE_ID ACTION_DATE T
---------- ----------- ------------------- -
1 1 04-07-2011 10:15:07 A
2 1 03-07-2011 10:15:07 B
3 1 02-07-2011 10:15:07 C
4 1 01-07-2011 10:15:07 D
5 2 23-06-2011 10:15:07 E
6 2 22-06-2011 10:15:07 F
7 2 21-06-2011 10:15:07 G
7 rows selected.
SQL> select employee_id
2 , min(action_date) min_date
3 , max(type) keep (dense_rank first order by action_date) min_date_type
4 , max(action_date) max_date
5 , max(type) keep (dense_rank last order by action_date) max_date_type
6 from my_transactions
7 group by employee_id
8 /
EMPLOYEE_ID MIN_DATE M MAX_DATE M
----------- ------------------- - ------------------- -
1 01-07-2011 10:15:07 D 04-07-2011 10:15:07 A
2 21-06-2011 10:15:07 G 23-06-2011 10:15:07 E
2 rows selected.
Regards,
Rob.
You could try to use analytical(or windowing functions)
select *
from
(select id, employee_id, action_date,type,
max(action_date) over (partition by employee_id) max_action_date,
min(action_date) over (partition by employee_id) min_action_date
from transaction)
where action_date in (max_action_date, min_action_date)
Related
I am new to oracle thus this question.
There is a table already existed and I have added a new column to it.
There are 5 rows and I do not want to use update table with where clause to insert the values one by one in the new column. Is there a statement like INSERT ALL to insert the values into the new column in one shot ?
Thanks
You can also use something like below which in-effect I would say is multiple update only, wrapped in single statement.
SQL> select * from test_upd;
ID1 ID2
---------- ----------
1
2
3
4
SQL> update test_upd a set a.id2 =
2 (select
3 case
4 when id1=1 then 100
5 when id1=2 then 200
6 when id1=3 then 300
7 else 5000 end
8 from test_upd b
9 where a.id1=b.id1);
4 rows updated.
SQL> select * from test_upd;
ID1 ID2
---------- ----------
1 100
2 200
3 300
4 5000
Use a MERGE statement:
MERGE INTO your_table dst
USING (
SELECT 1 AS id, 'aaa' AS newvalue FROM DUAL UNION ALL
SELECT 2, 'bbb' FROM DUAL UNION ALL
SELECT 3, 'ccc' FROM DUAL UNION ALL
SELECT 4, 'ddd' FROM DUAL UNION ALL
SELECT 5, 'eee' FROM DUAL
) src
ON (dst.id = src.id)
WHEN MATCHED THEN
UPDATE SET value = src.newvalue;
Which, if you have the table:
CREATE TABLE your_table (id, value) AS
SELECT 1, CAST(NULL AS VARCHAR2(3)) FROM DUAL UNION ALL
SELECT 2, NULL FROM DUAL UNION ALL
SELECT 3, NULL FROM DUAL UNION ALL
SELECT 4, NULL FROM DUAL UNION ALL
SELECT 5, NULL FROM DUAL;
Then, after the MERGE, the table contains:
ID
VALUE
1
aaa
2
bbb
3
ccc
4
ddd
5
eee
db<>fiddle here
I have a table like this:
Division
Region
Date of Last Visit
1
2
11/20/2021
1
2
11/18/2021
1
7
10/18/2021
1
7
11/19/2021
2
2
11/17/2021
2
3
09/20/2021
2
3
10/20/2021
I want to write a query that groups by the division and region columns and gives me the last 5 dates for each group separated by commas in a single column. Something like this:
Division
Region
Date of Last Visit
Today
Days since last visit
1
2
11/20/2021, 11/18/2021
sysdate
sysdate - max(date of last visit)
1
7
10/18/2021, 11/19/2021
sysdate
sysdate - max(date of last visit)
2
2
11/17/2021
sysdate
sysdate - max(date of last visit)
2
3
9/20/2021, 10/20/2021
sysdate
sysdate - max(date of last visit)
The last two columns are custom calculated columns that I also need for the final output table. Any help would be greatly appreciated as I have tried a lot of things but I keep getting errors about it not being grouped properly, possibly because of the two extra columns at the end. But even without that, I am not sure how to fetch only the last 5 dates per group in oracle.
Thanks!
You want to filter the greatest-n-per-group using the ROW_NUMBER analytic function and then aggregate:
SELECT division,
region,
LISTAGG(TO_CHAR(date_of_last_visit, 'DD/MM/YYYY'), ',')
WITHIN GROUP (ORDER BY date_of_last_visit DESC)
AS date_of_last_visit,
SYSDATE AS today,
TRUNC(SYSDATE - MAX(date_of_last_visit)) AS days_since_last_visit
FROM (
SELECT t.*,
ROW_NUMBER() OVER (PARTITION BY division, region
ORDER BY date_of_last_visit DESC) AS rn
FROM table_name t
)
WHERE rn <= 5
GROUP BY
division,
region
Which, for the sample data:
CREATE TABLE table_name (division, region, date_of_last_visit) as
select 1, 2, date '2021-11-20' from dual union all
select 1, 2, date '2021-11-18' from dual union all
select 1, 7, date '2021-10-18' from dual union all
select 1, 7, date '2021-11-19' from dual union all
select 2, 2, date '2021-11-17' from dual union all
select 2, 3, date '2021-09-20' from dual union all
select 2, 3, date '2021-10-20' from dual;
Outputs:
DIVISION
REGION
DATE_OF_LAST_VISIT
TODAY
DAYS_SINCE_LAST_VISIT
1
2
20/11/2021,18/11/2021
30-NOV-21
10
1
7
19/11/2021,18/10/2021
30-NOV-21
11
2
2
17/11/2021
30-NOV-21
13
2
3
20/10/2021,20/09/2021
30-NOV-21
41
db<>fiddle here
Here you go; read comments within code.
SQL> with test (division, region, datum) as
2 -- sample data
3 (select 1, 2, date '2021-11-20' from dual union all
4 select 1, 2, date '2021-11-18' from dual union all
5 select 1, 7, date '2021-10-18' from dual union all
6 select 1, 7, date '2021-11-19' from dual union all
7 select 2, 2, date '2021-11-17' from dual union all
8 select 2, 3, date '2021-09-20' from dual union all
9 select 2, 3, date '2021-10-20' from dual
10 ),
11 temp as
12 -- rank rows per division/region, sorted by date column in descending order
13 (select t.*,
14 rank() over (partition by division, region order by datum desc) rnk
15 from test t
16 )
17 -- select up to 5 last rows per division/region
18 select division, region,
19 listagg(datum, ', ') within group (order by datum) dates,
20 trunc(sysdate) today,
21 --
22 (select trunc(sysdate) - a.datum
23 from temp a
24 where a.division = t.division
25 and a.region = t.region
26 and a.rnk = 1) days_since
27 from temp t
28 where rnk <= 5
29 group by division, region
30 order by division, region;
DIVISION REGION DATES TODAY DAYS_SINCE
---------- ---------- ------------------------------ ---------- ----------
1 2 11/18/2021, 11/20/2021 11/30/2021 10
1 7 10/18/2021, 11/19/2021 11/30/2021 11
2 2 11/17/2021 11/30/2021 13
2 3 09/20/2021, 10/20/2021 11/30/2021 41
SQL>
I wrote query
select s_id from emp
where s_inv=12
i got results in this manner
1
2
3
4
5
but i want it in this format
1 2 3 4 5
If you need your result in a single column, you can use LISTAGG:
with emp(s_id, s_inv) as
(
select 1, 12 from dual union all
select 2, 12 from dual union all
select 3, 12 from dual union all
select 4, 12 from dual union all
select 5, 12 from dual
)
select listagg(s_id, ' ') within group (order by s_id)
from emp
where s_inv = 12
If you need to build many columns on the same row, you should first define how many columns will your result have
Suppose I have a table with 10 records/tuples. Now I want to update an attribute of 6th record with the same attribute of 1st record, 2nd-7th, 3rd-8th, 4th-9th, 5th-10th in a go i.e. without using cursor/loop. Use of any number of temporary table is allowed. What is the strategy to do so?
PostgreSQL (and probably other RDBMSes) let you use self-joins in UPDATE statements just as you can in SELECT statements:
UPDATE tbl
SET attr = t2.attr
FROM tbl t2
WHERE tbl.id = t2.id + 5
AND tbl.id >= 6
This would be easy with an update-with-join but Oracle doesn't do that and the closest substitute can be very tricky to get to work. Here is the easiest way. It involves a subquery to get the new value and a correlated subquery in the where clause. It looks complicated but the set subquery should be self-explanatory.
The where subquery really only has one purpose: it connects the two tables, much as the on clause would do if we could do a join. Except that the field used from the main table (the one being updated) must be a key field. As it turns out, with the self "join" being performed below, they are both the same field, but it is required.
Add to the where clause other restraining criteria, as shown.
update Tuples t1
set t1.Attr =(
select t2.Attr
from Tuples t2
where t2.Attr = t1.Attr - 5 )
where exists(
select t2.KeyVal
from Tuples t2
where t1.KeyVal = t2.KeyVal)
and t1.Attr > 5;
SqlFiddle is pulling a hissy fit right now so here the data used:
create table Tuples(
KeyVal int not null primary key,
Attr int
);
insert into Tuples
select 1, 1 from dual union all
select 2, 2 from dual union all
select 3, 3 from dual union all
select 4, 4 from dual union all
select 5, 5 from dual union all
select 6, 6 from dual union all
select 7, 7 from dual union all
select 8, 8 from dual union all
select 9, 9 from dual union all
select 10, 10 from dual;
The table starts out looking like this:
KEYVAL ATTR
------ ----
1 1
2 2
3 3
4 4
5 5
6 6
7 7
8 8
9 9
10 10
with this result:
KEYVAL ATTR
------ ----
1 1
2 2
3 3
4 4
5 5
6 1
7 2
8 3
9 4
10 5
My oracle version is 10.2.
It's very strange when a scalar subquery has an aggregate operation.
my table named t_test looked like this;
t_id t_name
1 1
2 1
3 2
4 2
5 3
6 3
query string looked like this;
select t1.t_id,
(select count(t_name)
from (select t2.t_name
from t_test t2
where t2.t_id=t1.t_id
group by t2.t_name)) a
from t_test t1
this query's result is,
t_id a
1 3
2 3
3 3
4 3
5 3
6 3
which is very weird,
take t1.t_id=1 for example,
select count(t_name)
from (select t2.t_name
from t_test t2
where t2.t_id=1
group by t2.t_name)
the result is 1,
somehow,the 'where' operator doesn't work,the result is exactly the same as I put my query like this:
select t1.t_id,
(select count(t_name)
from (select t2.t_name
from t_test t2
group by t2.t_name)) a
from t_test t1
why?
Can you post a cut-and-paste from SQL*Plus showing exactly what query you're running? The query you posted does not appear to be valid-- the alias t1 is not going to be valid in the subquery where you're referencing it. That makes me suspect that you're simplifying the problem to post here but you've accidentally left something important out.
SQL> ed
Wrote file afiedt.buf
1 with x as (
2 select 1 id, 1 name from dual union all
3 select 2,1 from dual union all
4 select 3,2 from dual union all
5 select 4,2 from dual union all
6 select 5,3 from dual union all
7 select 6,3 from dual
8 )
9 select t1.id
10 ,(select count(b.name)
11 from (select t2.name
12 from x t2
13 where t2.id = t1.id
14 group by t2.name) b) a
15* from x t1
SQL> /
where t2.id = t1.id
*
ERROR at line 13:
ORA-00904: "T1"."ID": invalid identifier
Presumably, it would be much more natural to write the query like this (assuming you really want to use a scalar subquery) where t1 is going to be a valid alias in the scalar subquery.
SQL> ed
Wrote file afiedt.buf
1 with x as (
2 select 1 id, 1 name from dual union all
3 select 2,1 from dual union all
4 select 3,2 from dual union all
5 select 4,2 from dual union all
6 select 5,3 from dual union all
7 select 6,3 from dual
8 )
9 select t1.id
10 ,(select count(t2.name)
11 from x t2
12 where t2.id = t1.id) cnt
13* from x t1
SQL> /
ID CNT
---------- ----------
1 1
2 1
3 1
4 1
5 1
6 1
6 rows selected.