We have a databade in postgresql ver 11.7 on the pgAdmin4 which has a table with 3 primary keys .We want to update each row with a random value between 1 and 10 .
We have found the desirable elements but we need a way to update only 1 row each time
the conditions are as follow :
1)The subjects much be in a specific semester which can be found in the table called "Courses"
2)then we must find the amkas of students who are registered ( register_status = 'approved')
and we need to upade the table called "Register" with random exam_grades with those conditions assuming the exam_grade is null
Update "Register" SET exam_grade = (SELECT floor(random() * 10 + 1)::int) WHERE course_code IN
(SELECT DISTINCT course_code FROM "Course" WHERE typical_year = 2 AND typical_season = 'spring' ) AND register_status = 'approved' AND exam_grade is null ;
Just that .Somehow we need the update to just be used on only one row and then just use a for loop to take it one by one.If there is any other information i should include ,please tell me
So the tables are as follows
Register:
amka(PK) serial_number(PK) course_code(PK) exam_grade final_grade lab_grade register_status
19 5 ΕΝΕ 501 null null null proposed
13 15 ΤΗΛ 417 2 2 null fail
13 15 ΤΗΛ 411 10 8.4 null pass
47 22 ΜΠΔ 433 6 null 9 approved
:
Course:
course_code(PK) typical_year typical_season units ects weight obligatory
ΑΓΓ 201 2 winter 2 4 1 true
ΜΑΘ 201 1 winter 4 6 1.5 true
ΜΑΘ 208 1 winter 3 5 1.5 false
The results that i want are
mka(PK) serial_number(PK) course_code(PK) exam_grade final_grade lab_grade register_status
19 5 ΕΝΕ 501 random null null approved
13 15 ΤΗΛ 417 random 2 null approved
13 15 ΤΗΛ 411 random 8.4 null approved
47 22 ΜΠΔ 433 random null 9 approved
new random in each row
but i only get 1 number which fills all of them
i hope with this edit things became clearer
Related
I have a table named "building" in PostgreSQL. It has several columns and millions of rows. Each row has a unique id. It looks like
id tags height building:levels area
1 apartment 58 m 17 109
2 apartment null null 111
3 shed 7 2 75sqm
4 greenhouse 6m 3 159
5 industrial 16 2;4 105
6 commercial 27 8 474
And I have another csv file with cleaned data for column height and building:levels. The csv looks like:
id height building:levels
1 58 17
3 7 2
4 6 3
5 16 4
6 27 8
I want to join the csv file back to the table on the server, and the final outcome might look like this:
id tags height building:levels area
1 apartment 58 17 109
2 apartment null null 111
3 shed 7 2 75sqm
4 greenhouse 6 3 159
5 industrial 16 4 105
6 commercial 27 8 474
I want to replace the values in height and building:levels where the id are the same in the table and the csv file. I've tried to import data from csv but it didn't replace the values, only adding new rows. How can I achieve this?
You can import the csv file data in a temporary table first :
CREATE TEMPORARY TABLE IF NOT EXISTS building_temp LIKE building ;
COPY building_temp (id, height, "building:levels") FROM your_csv_file.csv WITH options_list ;
See the manual for building the options_list.
and then update the building table from that temporary table
UPDATE building AS b
SET height = bt.height
, "building:levels" = bt."building:levels"
FROM building_temp AS bt
WHERE b.id = bt.id
I am working on a simple comment system where a user can comment on other comments, thus creating a hierarchy. To get the comments in a hierarchical order I am using Common Table Expression in Postgres.
Below are the fields and the query used:
id
user_id
parent_comment_id
message
WITH RECURSIVE CommentCTE AS (
SELECT id, parent_comment_id, user_id
FROM comment
WHERE parent_comment_id is NULL
UNION ALL
SELECT child.id, child.parent_comment_id, child.user_id
FROM comment child
JOIN CommentCTE
ON child.parent_comment_id = CommentCTE.id
)
SELECT * FROM CommentCTE
The above query returns records in a breadth first manner:
id parent_comment_id user_id
10 null 30
9 null 30
11 9 30
14 10 31
15 10 31
12 11 30
13 12 31
But can it be modified to achieve something like below where records are returned together for that comment set, in a depth first manner? The point is to get the data in this way to make rendering on the Front-end smoother.
id parent_comment_id user_id
9 null 30
11 9 30
12 11 30
13 12 31
10 null 30
14 10 31
15 10 31
Generally I solve this problem by synthesising a "Path" column which can be sorted lexically, e.g. 0001:0003:0006:0009 is a child of 0001:0003:0006. Each child entry can be created by concatenating the path element to the parent's path. You don't have to return this column to the client, just use it for sorting.
id parent_comment_id user_id sort_key
9 null 30 0009
11 9 30 0009:0011
12 11 30 0009:0011:0012
13 12 31 0009:0011:0012:0013
10 null 30 0010
14 10 31 0010:0014
15 10 31 0010:0015
The path element doesn't have to be anything in particular provided it sorts lexically in the order you want children at that level to sort, and is unique at that level. Basing it on an auto-incrementing ID is fine.
Using a fixed length path element is not strictly speaking necessary but makes it easier to reason about.
WITH RECURSIVE CommentCTE AS (
SELECT id, parent_comment_id, user_id,
lpad(id::text, 4) sort_key
FROM comment
WHERE parent_comment_id is NULL
UNION ALL
SELECT child.id, child.parent_comment_id, child.user_id,
concat(CommentCTE.sort_key, ':', lpad(id::text, 4))
FROM comment child
JOIN CommentCTE
ON child.parent_comment_id = CommentCTE.id
)
SELECT * FROM CommentCTE order by sort_key
I have a table that looks like this:
GroupID UserID Value
1 1 10
1 2 20
1 3 30
1 4 40
1 5 45
1 6 49
1 7 80
1 8 90
2 1 2
2 2 24
2 3 34
2 4 48
2 5 56
3 1 etc.
3 2
3 3
3 4
4 1
4 2
4 3
I am trying to write a LEAD function that will give me the midpoint between each value. To do this I have written the following:
SELECT
[GroupID]
, [UserID]+0.5
, (LEAD ([Value], 1) OVER (ORDER BY GroupID, UserID) + [Value])/2 as [Value]
from dbo.myTable
The problem with this function is that when it gets to the last User in the group, it gives me a bad value because it's taking the [Value] on the current row and the value from the next row.
What I want to do is stop it when it reaches the maximum UserID for each Group. In other words, when it gets to GroupID = 1 and UserID = 8, it should end and start at the next Group. I do not want a row that looks like this:
GroupID UserID Value
1 8.5 46
I could run a DELETE statement after I INSERT the rows into the original table, but I don't have anything to identify when a row is the "maximum" User for it's Group. Ideally, I would like to somehow tell the lead statement not to calculate it in the first place.
I have an application which logs changes to records in the "production" table to a "history" table. The history table is basically a field for field copy of the production table, with a few extra columns like last modified date, last modified by user, etc.
This works well because we get a snapshot of the record anytime the record changes. However, it makes it hard to determine unique status changes to a record. An example is below.
BoxID StatusID SubStatusID ModifiedTime
1 4 27 2011-08-11 15:31
1 4 11 2011-08-11 15:28
1 4 11 2011-08-10 09:07
1 5 14 2011-08-09 08:53
1 5 14 2011-08-09 08:19
1 4 11 2011-08-08 14:15
1 4 9 2011-07-27 15:52
1 4 9 2011-07-27 15:49
1 2 8 2011-07-26 12:00
As you can see in the above table (data comes from the real system with other fields removed for brevity and security) BoxID 1 has had 9 changes to the production record. Some of those updates resulted in statuses being changed and some did not, which means other fields (those not shown) have changed.
I need to be able, in TSQL, to extract from this data the unique status changes. The output I am looking for, given the above input table, is below.
BoxID StatusID SubStatusID ModifiedTime
1 4 27 2011-08-11 15:31
1 4 11 2011-08-10 09:07
1 5 14 2011-08-09 08:19
1 4 11 2011-08-08 14:15
1 4 9 2011-07-27 15:49
1 2 8 2011-07-26 12:00
This is not as easy as grouping by StatusID and SubStatusID and taking the min(ModifiedTime) then joining back into the history table since statuses can go backwards as well (see StatusID 4, SubStatusID 11 gets set twice).
Any help would be greatly appreciated!
Does this do work for you
;WITH Boxes_CTE AS
(
SELECT Boxid, StatusID, SubStatusID, ModifiedTime,
ROW_NUMBER() OVER (PARTITION BY Boxid ORDER BY ModifiedTime) AS SEQUENCE
FROM Boxes
)
SELECT b1.Boxid, b1.StatusID, b1.SubStatusID, b1.ModifiedTime
FROM Boxes_CTE b1
LEFT OUTER JOIN Boxes_CTE b2 ON b1.Boxid = b2.Boxid
AND b1.Sequence = b2.Sequence + 1
WHERE b1.StatusID <> b2.StatusID
OR b1.SubStatusID <> b2.SubStatusID
OR b2.StatusID IS NULL
ORDER BY b1.ModifiedTime DESC
;
Select BoxID,StatusID,SubStatusID FROM Staty CurrentStaty
INNER JOIN ON
(
Select BoxID,StatusID,SubStatusID FROM Staty PriorStaty
)
Where Staty.ModifiedTime=
(Select Max(PriorStaty.ModifiedTime) FROM PriorStaty
Where PriortStaty.ModifiedTime<Staty.ModifiedTime)
AND Staty.BoxID=PriorStaty.BoxID
AND NOT (
Staty.StatusID=PriorStaty.StatusID
AND
Staty.SubStatusID=PriorStaty.StatusID
)
I use Oracle 10g and I have a table that stores a snapshot of data on a person for a given day. Every night an outside process adds new rows to the table for any person whose had any changes to their core data (stored elsewhere). This allows a query to be written using a date to find out what a person 'looked' like on some past day. A new row is added to the table even if only a single aspect of the person has changed--the implication being that many columns have duplicate values from slice to slice since not every detail changed in each snapshot.
Below is a data sample:
SliceID PersonID StartDt Detail1 Detail2 Detail3 Detail4 ...
1 101 08/20/09 Red Vanilla N 23
2 101 08/31/09 Orange Chocolate N 23
3 101 09/15/09 Yellow Chocolate Y 24
4 101 09/16/09 Green Chocolate N 24
5 102 01/10/09 Blue Lemon N 36
6 102 01/11/09 Indigo Lemon N 36
7 102 02/02/09 Violet Lemon Y 36
8 103 07/07/09 Red Orange N 12
9 104 01/31/09 Orange Orange N 12
10 104 10/20/09 Yellow Orange N 13
I need to write a query that pulls out time slices records where some pertinent bits, not the whole record, have changed. So, referring to the above, if I only want to know the slices in which Detail3 has changed from its previous value, then I would expect to only get rows having SliceID 1, 3 and 4 for PersonID 101 and SliceID 5 and 7 for PersonID 102 and SliceID 8 for PersonID 103 and SliceID 9 for PersonID 104.
I'm thinking I should be able to use some sort of Oracle Hierarchical Query (using CONNECT BY [PRIOR]) to get what I want, but I have not figured out how to write it yet. Perhaps YOU can help.
Thanks you for your time and consideration.
Here is my take on the LAG() solution, which is basically the same as that of egorius, but I show my workings ;)
SQL> select * from
2 (
3 select sliceid
4 , personid
5 , startdt
6 , detail3 as new_detail3
7 , lag(detail3) over (partition by personid
8 order by startdt) prev_detail3
9 from some_table
10 )
11 where prev_detail3 is null
12 or ( prev_detail3 != new_detail3 )
13 /
SLICEID PERSONID STARTDT N P
---------- ---------- --------- - -
1 101 20-AUG-09 N
3 101 15-SEP-09 Y N
4 101 16-SEP-09 N Y
5 102 10-JAN-09 N
7 102 02-FEB-09 Y N
8 103 07-JUL-09 N
9 104 31-JAN-09 N
7 rows selected.
SQL>
The point about this solution is that it hauls in results for 103 and 104, who don't have slice records where detail3 has changed. If that is a problem we can apply an additional filtration, to return only rows with changes:
SQL> with subq as (
2 select t.*
3 , row_number () over (partition by personid
4 order by sliceid ) rn
5 from
6 (
7 select sliceid
8 , personid
9 , startdt
10 , detail3 as new_detail3
11 , lag(detail3) over (partition by personid
12 order by startdt) prev_detail3
13 from some_table
14 ) t
15 where t.prev_detail3 is null
16 or ( t.prev_detail3 != t.new_detail3 )
17 )
18 select sliceid
19 , personid
20 , startdt
21 , new_detail3
22 , prev_detail3
23 from subq sq
24 where exists ( select null from subq x
25 where x.personid = sq.personid
26 and x.rn > 1 )
27 order by sliceid
28 /
SLICEID PERSONID STARTDT N P
---------- ---------- --------- - -
1 101 20-AUG-09 N
3 101 15-SEP-09 Y N
4 101 16-SEP-09 N Y
5 102 10-JAN-09 N
7 102 02-FEB-09 Y N
SQL>
edit
As egorius points out in the comments, the OP does want hits for all users, even if they haven't changed, so the first version of the query is the correct solution.
In addition to OMG Ponies' answer: if you need to query slices for all persons, you'll need partition by:
SELECT s.sliceid
, s.personid
FROM (SELECT t.sliceid,
t.personid,
t.detail3,
LAG(t.detail3) OVER (
PARTITION BY t.personid ORDER BY t.startdt
) prev_val
FROM t) s
WHERE (s.prev_val IS NULL OR s.prev_val != s.detail3)
I think you'll have better luck with the LAG function:
SELECT s.sliceid
FROM (SELECT t.sliceid,
t.personid,
t.detail3,
LAG(t.detail3) OVER (PARTITION BY t.personid ORDER BY t.startdt) 'prev_val'
FROM TABLE t) s
WHERE s.personid = 101
AND (s.prev_val IS NULL OR s.prev_val != s.detail3)
Subquery Factoring alternative:
WITH slices AS (
SELECT t.sliceid,
t.personid,
t.detail3,
LAG(t.detail3) OVER (PARTITION BY t.personid ORDER BY t.startdt) 'prev_val'
FROM TABLE t)
SELECT s.sliceid
FROM slices s
WHERE s.personid = 101
AND (s.prev_val IS NULL OR s.prev_val != s.detail3)