How do i update table structured like this:
id[pkey] | parent_id | position
1 1
2 1
3 1
4 1
5 1
6 2
7 2
8 2
9 2
10 3
11 3
12 3
...and so on
to achieve this result:
id[pkey] | parent_id | position
1 1 1
2 1 2
3 1 3
4 1 4
5 1 5
6 2 1
7 2 2
8 2 3
9 2 4
10 3 1
11 3 2
12 3 3
...and so on
I was thinking about somehow mixing
SELECT DISTINCT parent_id FROM cats AS t;
with
CREATE SEQUENCE dpos;
UPDATE cats t1 SET position = nextval('dpos') WHERE t.parent_id = t1.parent_id;
DROP SEQUENCE dpos;
although im not really experienced with postgres, and not sure how to use some kind of FOREACH. I appreciate any help
You can get the incremental number using row_number(). The question is how to assign it to a particular row. Here is one method using a join:
update cats
set position = c2.newpos
from (select c2.*, c2.ctid as c_ctid,
row_number() over (partition by c2.parent_id order by NULL) as seqnum
from cats c2
) c2
where cats.parent_id = c2.parent_id and cats.ctid = c2.c_ctid;
Use row_number function
select parent_id,
row_number() over (partition by parent_id order by parent_id) as position_id from table
Try this:
UPDATE table_name set table_name.dataID = v_table_name.rn
FROM
(
SELECT row_number() over (partition by your_primaryKey order by your_primaryKey) AS rn, id
FROM table_name
) AS v_table_name
WHERE v_table_name.your_primaryKey = v_table_name.your_primaryKey;
Related
I seek to find the maximum timestamp (ob.create_ts) for each group of marketid's (ob.marketid), joining tables obe (ob.orderbookid = obe.orderbookid) and market (ob.marketid = m.marketid). Although there are a number of solutions posted like this for a single table, when I join multiple tables, I get redundant results. Sample table and desired results below:
table: ob
orderbookid
marketid
create_ts
1
1
1664635255298
2
1
1664635255299
3
1
1664635255300
4
2
1664635255301
5
2
1664635255302
6
2
1664635255303
table: obe
orderbookentryid
orderbookid
entryname
1
1
'entry-1'
2
1
'entry-2'
3
1
'entry-3'
4
2
'entry-4'
5
2
'entry-5'
6
3
'entry-6'
7
3
'entry-7'
8
4
'entry-8'
9
5
'entry-9'
10
6
'entry-10'
table: m
marketid
marketname
1
'market-1'
2
'market-2'
desired results
ob.orderbookid
ob.marketid
obe.orderbookentryid
obe.entryname
m.marketname
3
1
6
'entry-6'
'market-1'
3
1
7
'entry-7'
'market-1'
6
2
10
'entry-10'
'market-2'
Use ROW_NUMBER() to get a properly filtered ob table. Then JOIN the other tables onto that!
WITH
ob_filtered AS (
SELECT
orderbookid,
marketid
FROM
(
SELECT
*,
ROW_NUMBER() OVER (
PARTITION BY
marketid
ORDER BY
create_ts DESC
) AS create_ts_rownumber
FROM
ob
) ob_with_rownumber
WHERE
create_ts_rownumber = 1
)
SELECT
ob_filtered.orderbookid,
ob_filtered.marketid,
obe.orderbookentryid,
obe.entryname,
m.marketname
FROM
ob_filtered
JOIN m
ON m.marketid = ob_filtered.marketid
JOIN obe
ON ob_filtered.orderbookid = obe.orderbookid
;
I wonder how to update order in this table for many-to-many relationship using SQL based on PostsId.
So my table now looks like:
I'm using SQL Server
BlogsId
PostsId
Order
1
1
1
0
2
2
1
0
3
3
2
0
3
4
2
0
3
5
3
0
3
6
3
0
but I want to update Order using SQL to this:
BlogsId
PostsId
Order
1
1
1
1
2
2
1
2
3
3
2
1
3
4
2
2
3
5
3
1
3
6
3
2
So for example: Blog with Id 3 is the first blog in Post with Id 2, Blog with Id 4 is the second Blog in Post with Id 2 and etc...
I've tried this:
DECLARE #myVar int
SET #myVar = 0
UPDATE [dbo].[BlogPost]
SET #myVar = [Order] = #myVar + 1
but then I got this:
BlogsId
PostsId
Order
1
1
1
1
2
2
1
2
3
3
2
3
3
4
2
4
3
5
3
5
3
6
3
6
So, I think I should do something in WHERE part (with Distinct maybe) but I don't know exactly what. I could write something in C# to do what I want but I don't know how to write something like this in SQL.
Physically maintaining an order or sequence of rows is rarely a good idea and can lead to data inconsistencies and other unforseen issues.
You would be better off creating a view that provides the additional Order column which you can do using row_number()
Create view BlogPosts as
select *,
Row_Number() over(partition by PostsId order by BlogsId) as [Order]
from blogpost;
If you really want to update an actual column in the table you could use a CTE
with b as (
select *,
Row_Number() over(partition by PostsId order by BlogsId) as seq
from blogpost
)
update b
set [Order] = seq;
You can update from a calculated row_number.
update t
set [Order] = rn
from (
select BlogsId, PostsId, [Order]
, rn = row_number() over (partition by PostsId order by BlogsId asc)
from BlogPost
) t
where ([Order] is null or [Order]!=rn);
select *
from BlogPost
order by BlogsId, PostsId
BlogsId
PostsId
Order
1
1
1
2
1
2
3
2
1
4
2
2
5
3
1
6
3
2
Demo on db<>fiddle here
I have this table with the following records:
table1
id ele_id_1 ele_val ele_id_2
1 2 123 1
1 1 abc 1
1 4 xyz 2
1 4 456 1
2 5 22 1
2 4 344 1
2 3 6 1
2 2 Test Name 1
2 1 Hello 1
I am trying to add position for each id when ele_id_1 and ele_id_2 is order by ASC.
Here is the output:
id ele_id_1 ele_val ele_id_2 position
1 2 123 1 2
1 1 abc 1 1
1 4 xyz 2 4
1 4 456 1 3
2 5 22 1 5
2 4 344 1 4
2 3 6 1 3
2 2 Test Name 1 2
2 1 Hello 1 1
I have 34 million rows in table1, so would like to use an efficient way of doing this.
Any idea on how I can add position with values?
I think you want row_number() used like this:
select row_number() over (partition by id
order by ele_id_1, ele_id_2
) as position
Oracle can use an index for this, on (id, ele_id_1, ele_id_2).
I should note that for your example data order by ele_id_1, ele_id_2 and order by ele_id_2, ele_id_1 produce the same result. Your question suggests that you want the first.
So, you would get
id ele_id_1 ele_val ele_id_2 position
1 1 123 2 2
1 1 abc 1 1
1 4 xyz 2 4
1 4 456 1 3
Rather than:
id ele_id_1 ele_val ele_id_2 position
1 1 123 2 3
1 1 abc 1 1
1 4 xyz 2 4
1 4 456 1 2
EDIT:
If you want to update the data, then merge is probably the best approach.
MERGE INTO <yourtable> dest
USING (select t.*,
row_number() over (partition by id
order by ele_id_1, ele_id_2
) as new_position
from <yourtable> t
) src
ON dest.id = src.id AND
dest.ele_id_1 = src.ele_id_1 AND
dest.ele_id_2 = src.ele_id_2
WHEN MATCHED THEN UPDATE
SET desc.postition = src.new_position;
Note that updating all the rows in a table is an expensive operation. Truncating the table and recreating it might be easier:
create table temp_t as
select t.*,
row_number() over (partition by id
order by ele_id_1, ele_id_2
) as new_position
from t;
truncate table t;
insert into t ( . . . )
select . . . -- all columns but position
from temp_t;
However, be very careful if you truncate the table. Be sure to back it up first!
I have a table of list items. There is a ListID column used as an identifier to group the list items together. Is there a sane way to give every item a sort order, starting at 0 per list and incremental by one per item.
Basically, I need to populate the following SortOrder Column values for a large number of entries/ListIDs.
ID ListID SortOrder
1 1 0
2 0 0
3 1 1
4 0 1
5 1 2
6 0 2
7 2 0
8 2 1
9 2 2
You can use ROW_NUMBER() with a PARTITION on the ListId field for this:
Select Id, ListId,
Row_Number() Over (Partition By ListId Order By Id) -1 As SortOrder
From YourTable
Order By Id
I think you want:
WITH toupdate as (
SELECT t.*,
ROW_NUMBER() OVER (PARTITION BY ListId Order By id) as new_SortOrder
FROM tableName
)
UPDATE toupdate a
SET sortorder = new_sort_order;
SQL Server has the nice ability to update a subquery or CTE under some circumstances.
Do you need to persist the order of lists containing items that are shared between lists? If so, perhaps variations on this schema would work for you.
Item
id label
1 A
2 B
3 C
4 D
List
id listName
1 abc list
2 cbd list
3 aaa list
ListMembership
id listId itemId order
1 1 1 1
2 1 2 2
3 1 3 3
4 2 2 2
5 2 3 1
6 2 4 3
7 3 1 1
8 3 1 2
9 3 1 3
usage:
select i.label from listMembership as lm
join Item as i on i.id=lm.itemId
where lm.listId=2
order by lm.order
yields:
label
C
B
D
I have a table containing items in a priority order as such:
id priority
1 1
2 2
3 3
4 8
5 3
6 4
Currently I retrieve items (SQL Server) in priority order, although a random item when there are matching priorities using the following query:
select item
from table
order by priority, newid()
This will return
id priority
1 1
2 2
3 3
5 3
6 4
4 8
or
id priority
1 1
2 2
5 3
3 3
6 4
4 8
So it's approximately 50/50 traffic
I now have a requirement to only retrieve one row of the rows when there are two matching priorities, for example..
id priority
1 1
2 2
3 3
6 4
4 8
or
id priority
1 1
2 2
5 3
6 4
4 8
You can use ROW_NUMBER, presuming SQL-Server (because of NEWID):
WITH CTE AS
(
SELECT t.*, RN = ROW_NUMBER() OVER (PARTITION BY Priority
ORDER BY ID)
FROM dbo.table t
)
SELECT * FROM CTE WHERE RN = 1
If these are all columns you could also use this sql:
SELECT MIN(t.ID) AS ID, t.Priority
FROM dbo.table t
GROUP BY t.priority
Update "No, I need to be able to get a random row when two (or more) priorities match"
Then i have misunderstood your requirement. You can use ORDER BY NEWID:
WITH CTE AS
(
SELECT t.*, RN = ROW_NUMBER() OVER (PARTITION BY Priority
ORDER BY NEWID())
FROM dbo.table t
)
SELECT * FROM CTE WHERE RN = 1