I have a table that I would like to update one column data on every nth row if it meets row requirement.
My table has many columns but the key are Object_Id (in case this could be useful for creating temp table)
But the one I'm trying to update is online_status, it looks like below, but on bigger scales so I usually have 10rows that has same time but they all have %Online% in it and in total around 2000 rows (with Online and about another 2000 with Offline). I just need to update every 2-4 rows of those 10 that are repeating itself.
Table picture here: (for some reason table formatting doesn't come up good)
Table
So what I tried is: This pulls a list of every 3rd record that matches criteria Online, I just need a way to update it but can't get through this.
SELECT * FROM (SELECT *, row_number() over() rn FROM people
WHERE online_status LIKE '%Online%') foo WHERE online_status LIKE '%Online%' AND foo.rn % 3 =0
What I also tried is:
However this has updated every single row. not the ones I needed.
UPDATE people
SET online_status = 'Offline 00:00-24:00'
WHERE people.Object_id IN
(SELECT *
FROM
(SELECT people.Object_id, row_number() over() rn FROM people
WHERE online_status LIKE '%Online%') foo WHERE people LIKE '%Online%' AND foo.rn % 3 =0);
Is there a way to take list from Select code above and simply update it or run a few scripts that could add it to like temp table and store object ids, and the next script would update main table if object id would match temp table.
Thank you for any help :)
Don't select other columns but Object_id in the subquery at WHERE people.Object_id IN (..)
UPDATE people
SET online_status = 'Offline 00:00-24:00'
WHERE Object_id IN
( SELECT Object_id
FROM
( SELECT p.Object_id, row_number() over() rn
FROM people p
WHERE p.online_status LIKE '%Online%') foo
WHERE foo.rn % 3 = 0
);
Related
I have two tables:
And I want to add GTIN from table 2 to table 1 based on brand name. Though I cant use = or like because as you see in highlighted row they are not fully matched.
For example
Second row in table 1, suppose to have first GTIN from table 2 because both are Ziagen 300mg tablet. However all of what I tried failed to match all row correctly.
Postgres has a pg_trgm module described here. Start with a cross join joining both tables and calculate the similarity(t1.brand,t2.brand) function, which returns the real number.
Next filter the results based on some heuristic number. Then narrow down with choosing single best match using row_number() window function.
The results might be not accurate, you could improve it by taking generic similarity into account as well.
with cross_similarity(generic1,brand1,gtin,brand2,generic2,sim) as (
select *, similarity(t1.brand, t2.brand) as sim
from t1,
t2
where similarity(t1.brand, t2.brand) > 0
)
, max_similarity as (
select *,
row_number() over (partition by gtin order by sim desc) as best_match_rank
from cross_similarity
)
select * from max_similarity where best_match_rank =1;
I would like to see a most concise way to do what is outlined in this SO question: Sum values from multiple rows into one row
that is, combine multiple rows while summing a column.
But how to then delete the duplicates. In other words I have data like this:
Person Value
--------------
1 10
1 20
2 15
And I want to sum the values for any duplicates (on the Person col) into a single row and get rid of the other duplicates on the Person value. So my output would be:
Person Value
-------------
1 30
2 15
And I would like to do this without using a temp table. I think that I'll need to use OVER PARTITION BY but just not sure. Just trying to challenge myself in not doing it the temp table way. Working with SQL Server 2008 R2
Simply put, give me a concise stmt getting from my input to my output in the same table. So if my table name is People if I do a select * from People on it before the operation that I am asking in this question I get the first set above and then when I do a select * from People after the operation, I get the second set of data above.
Not sure why not using Temp table but here's one way to avoid it (tho imho this is an overkill):
UPDATE MyTable SET VALUE = (SELECT SUM(Value) FROM MyTable MT WHERE MT.Person = MyTable.Person);
WITH DUP_TABLE AS
(SELECT ROW_NUMBER()
OVER (PARTITION BY Person ORDER BY Person) As ROW_NO
FROM MyTable)
DELETE FROM DUP_TABLE WHERE ROW_NO > 1;
First query updates every duplicate person to the summary value. Second query removes duplicate persons.
Demo: http://sqlfiddle.com/#!3/db7aa/11
All you're asking for is a simple SUM() aggregate function and a GROUP BY
SELECT Person, SUM(Value)
FROM myTable
GROUP BY Person
The SUM() by itself would sum up the values in a column, but when you add a secondary column and GROUP BY it, SQL will show distinct values from the secondary column and perform the aggregate function by those distinct categories.
We have a table which keeps the log of internet usage inside our company. this table is filled by a software bought by us and we cannot make any changes to its table. This table does not have a unique key or index (to make the data writing faster as its developers say)
I need to read the data in this table to create real time reports of internet usage by our users.
currently I'm reading data from this table in chunks of 1000 records. My problem is keeping the last record I have read from the table, so I can read the next 1000 records.
what is the best possible solution to this problem?
by the way, earlier records may get deleted by the software as needed if the database file size gets big.
Depending on your version of SQL Server, you can use row_number(). Once the row_number() is assigned, then you can page through the records:
select *
from
(
select *,
row_number() over(order by id) rn
from yourtable
) src
where rn between 1 and 1000
Then when you want to get the next set of records, you could change the values in the WHERE clause to:
where rn between 1001 and 2000
Based on your comment that the data gets deleted, I would do the following.
First, insert the data into a temptable:
select *, row_number() over(order by id) rn
into #temp
from yourtable
Then you can select the data by row number in any block as needed.
select *
from #temp
where rn between 1 and 1000
This would also help;
declare #numRecords int = 1000 --Number of records needed per request
declare #requestCount int = 0 --Request number starting from 0 and increase 1 by 1
select top (#numRecords) *
from
(
select *, row_number() over(order by id) rn
from yourtable
) T
where rn > #requestCount*#numRecords
EDIT: As per comments
CREATE PROCEDURE [dbo].[select_myrecords]
--Number of records needed per request
declare #NumRecords int --(= 1000 )
--Datetime of the LAST RECORD of previous result-set or null for first request
declare #LastDateTime datetime = null
AS
BEGIN
select top (#NumRecords) *
from yourtable
where LOGTime < isnull(#LastDateTime,getdate())
order by LOGTime desc
END
Without any index you cannot efficiently select the "last" records. The solution will not scale. You cannot use "real-time" and "repeated table scans of a big logging table" in the same sentence.
Actually, without any unique identification attribute for each row you cannot even determine what's new (proof: say, you had a table full of thousands of booleans. How would you determine which ones are new? They cannot be told apart! You cannot find out.). There must be something you can use, like a combination of DateTime, IP or so. Or, you can add an IDENTITY column which is likely to be transparent to the software you use.
Probably, the software you use will tolerate you creating an index on some ID or DateTime column as this is transparent to the software. It might create more load, so be sure to test it (my guess: you'll be fine).
So we had a duplicate SQL scripts running on our server and didn't realize it till just recently. Essentially I have many rows where there are 2 entries with the same column x (crn).
The initially got entered with the same column y (status) as well. Our application has users update the column y (status). However now we have 2 rows one with a status of 'S' and one with a status of something other than 'S'. My goal:
DELETE everything from the table WHERE there is a duplicate CRN and the STATUS is S. I don't want to delete rows unless there is a duplicate, but if there is, I only want to delete the row with a status of 'S'. Also, I'd rather not delete both records if both have a status of S, but if I do, that isn't such a big deal because I will get the courses again in the next download.
I have started making a select statement to query the rows I want, but don't know how to do the ONLY SELECT IF DUPLICATE EXISTS part. I feel like I need to UNION or LEFT JOIN or something to only get records if a duplicate exists.
SELECT * FROM
cas_usuECourses
WHERE
crn IN (SELECT crn FROM cas_usuECourses GROUP BY crn having count(1) > 1)
AND status = 'S'
AND termCode = 201320
EDIT: Is there a way to say... the above, but if both dups have 'S' only delete one of them?
EDIT: I "think" this looks good to me. Any thoughts?
SELECT id FROM (
SELECT id, Row_Number() Over (Partition By crn ORDER BY id DESC) as ranking
FROM cas_usuECourses
WHERE status = 'S'
AND termCode = 201320
) as ranking
WHERE ranking = 1
I think this will give me all the ids where the status is 'S', and if there are two with 'S' this will give me the one that was created second. I found out that every entry in our termCode has duplicates, so... don't need to worry about checking for the duplicates.
If you could add one column to your table and fill it with distinct values, it would be trivial - you could target each row.
Otherwise, after your initial step, I would generally open a cursor on your subselect with status S to select only crn's where both statuses are 'S', and in each loop iteration delete top 1 record with appropriate crn. That way you can get rid of duplicate crn/status pairs.
i have loanTable that contain two field loan_id and status
loan_id status
==============
1 0
2 9
1 6
5 3
4 5
1 4 <-- How do I select this??
4 6
In this Situation i need to show the last Status of loan_id 1 i.e is status 4. Can please help me in this query.
Since the 'last' row for ID 1 is neither the minimum nor the maximum, you are living in a state of mild confusion. Rows in a table have no order. So, you should be providing another column, possibly the date/time when each row is inserted, to provide the sequencing of the data. Another option could be a separate, automatically incremented column which records the sequence in which the rows are inserted. Then the query can be written.
If the extra column is called status_id, then you could write:
SELECT L1.*
FROM LoanTable AS L1
WHERE L1.Status_ID = (SELECT MAX(Status_ID)
FROM LoanTable AS L2
WHERE L2.Loan_ID = 1);
(The table aliases L1 and L2 could be omitted without confusing the DBMS or experienced SQL programmers.)
As it stands, there is no reliable way of knowing which is the last row, so your query is unanswerable.
Does your table happen to have a primary id or a timestamp? If not then what you want is not really possible.
If yes then:
SELECT TOP 1 status
FROM loanTable
WHERE loan_id = 1
ORDER BY primaryId DESC
-- or
-- ORDER BY yourTimestamp DESC
I assume that with "last status" you mean the record that was inserted most recently? AFAIK there is no way to make such a query unless you add timestamp into your table where you store the date and time when the record was added. RDBMS don't keep any internal order of the records.
But if last = last inserted, that's not possible for current schema, until a PK addition:
select top 1 status, loan_id
from loanTable
where loan_id = 1
order by id desc -- PK
Use a data reader. When it exits the while loop it will be on the last row. As the other posters stated unless you put a sort on the query, the row order could change. Even if there is a clustered index on the table it might not return the rows in that order (without a sort on the clustered index).
SqlDataReader rdr = SQLcmd.ExecuteReader();
while (rdr.Read())
{
}
string lastVal = rdr[0].ToString()
rdr.Close();
You could also use a ROW_NUMBER() but that requires a sort and you cannot use ROW_NUMBER() directly in the Where. But you can fool it by creating a derived table. The rdr solution above is faster.
In oracle database this is very simple.
select * from (select * from loanTable order by rownum desc) where rownum=1
Hi if this has not been solved yet.
To get the last record for any field from a table the easiest way would be to add an ID to each record say pID. Also say that in your table you would like to hhet the last record for each 'Name', run the simple query
SELECT Name, MAX(pID) as LastID
INTO [TableName]
FROM [YourTableName]
GROUP BY [Name]/[Any other field you would like your last records to appear by]
You should now have a table containing the Names in one column and the last available ID for that Name.
Now you can use a join to get the other details from your primary table, say this is some price or date then run the following:
SELECT a.*,b.Price/b.date/b.[Whatever other field you want]
FROM [TableName] a LEFT JOIN [YourTableName]
ON a.Name = b.Name and a.LastID = b.pID
This should then give you the last records for each Name, for the first record run the same queries as above just replace the Max by Min above.
This should be easy to follow and should run quicker as well
If you don't have any identifying columns you could use to get the insert order. You can always do it like this. But it's hacky, and not very pretty.
select
t.row1,
t.row2,
ROW_NUMBER() OVER (ORDER BY t.[count]) AS rownum from (
select
tab.row1,
tab.row2,
1 as [count]
from table tab) t
So basically you get the 'natural order' if you can call it that, and add some column with all the same data. This can be used to sort by the 'natural order', giving you an opportunity to place a row number column on the next query.
Personally, if the system you are using hasn't got a time stamp/identity column, and the current users are using the 'natural order', I would quickly add a column and use this query to create some sort of time stamp/incremental key. Rather than risking having some automation mechanism change the 'natural order', breaking the data needed.
I think this code may help you:
WITH cte_Loans
AS
(
SELECT LoanID
,[Status]
,ROW_NUMBER() OVER(ORDER BY (SELECT 1)) AS RN
FROM LoanTable
)
SELECT LoanID
,[Status]
FROM LoanTable L1
WHERE RN = ( SELECT max(RN)
FROM LoanTable L2
WHERE L2.LoanID = L1.LoanID)