I'm wondering how I would go about writing a query to split a table into 3 segments. When I've had to split a table into 2 before I've always based it off the rownum and doing a mod on it. I know I could again use rownum and select based on ranges, but if the list varies in record count each time the queries are run they will have to be updated.
Any thoughts?
Why can't you continue to use MOD, as in MOD(rownum, 3) = 0, 1 or 2? If it worked for 2, why not 3?
Related
I need generate serial number in Oracle SQL Query..
Example:
rownum (1,2..9,10,11..18,19,20..N)
my_srl_no (1,2..9,1,2..9,1,2..N)
What you are looking for is the modulo function MOD (https://docs.oracle.com/en/database/oracle/oracle-database/19/sqlrf/MOD.html#GUID-E12A3928-2C50-45B0-B8C3-82432C751B8C).
If it's really rownum you want to deal with:
mod(rownum - 1, 9) + 1
but usually you would rather use ROW_NUMBER in order to number your rows by some sort criteria. Anyway, the math stays the same.
I need some help on this one. I have a query that I need to make work but I need to limit it by the results of another query.
SELECT ItemID, ItemNums
FROM dbo.Tables
ItemNums is a varchar field that is used to store the strings of the various item numbers.
This produces the following.
ItemID ItemNums
1 1, 4, 5
2 1, 3, 4, 5
3 2
4 4
5 1
I have another table that has each item number as an INT that I need to use to pull all ItemIDs that have the associated ItemNums
Something like this.
SELECT *
FROM dbo.Tables
WHERE ItemNums IN (4,5)
Any help would be appreciated.
If possible, you should change your database schema. In general, it's not good to store comma delimited lists in a relational database.
However, if that's not an option, here's one way using a join with like:
select *
from dbo.Tables t
join dbo.SecondTable st on ', '+t.ItemNums+',' like '%, '+st.ItemNumId+',%'
This concatenates commas to the beginning and end of the itemnums to ensure you only match on the specific ids.
I personally would recommend normalizing your dbo.tables.
It would be better as:
ItemID ItemNums
1 1
1 4
1 5
2 1
etc.
Then you can use a join or a sub query to pull out the rows with ItemNums in some list.
Otherwise, it's going to be a mess and not very fast.
I am new to SQL and I am not sure how to properly search my question so I will ask here.
Please see this link to see the SQL tables and queries I am working with
In this example there are 6 rows and I am limiting my search to start at the first index and give me at most 2. However, I would like to know the index of the row that has id 1.
When I use the query I describe in sqlfiddle, It shows me rows with id 5 and 23. But it doesn't include the row with id 1. However, I need to know the index of the row with id 1..
click here to see the full list
The link above prints out all of the rows and we can see that index 3 has the row containing id 1.
However I need to know that index without asking for the entire Array.
Why is this important? Well, lets say that we have 1 million rows. And if I ask for a million rows, that would mean allocating an array of one million. I could parse the array until I find the id I am looking for. However, allocating a million is way too costly.
Lets say for example that the row I am looking for resides in index 26, But I make my query so that it starts at index 0 and limits to 10. The array that I get from this query would not contain index 26. However I still need to know that it IS at index 26.
So this magic query would give me two things:
the top ten rows of the sorted rows
the index of a specified id (e.g. id of 1) regardless of its placement in the list.
Is this a possible query?
Clarification:
I use the word index to mean the row number.
If a we query a list of names from the db, we could get something like this:
bob
frank
dawn
then bob would be at index 0, frank would be at index 1 and dawn at index 2.
If I ORDER BY name ASC then the list of names would become
bob
dawn
frank
bob would be index 0 dawn would be index 1 and frank would be index 2.
I hope this makes things more clear.
If you want the row number, use the row_number() function:
SELECT *
FROM (SELECT ud.id, ud.team_name, ui.name, ui.date_created,
row_number() over (order by ui.name, ui.id) as rownumber
FROM user_data ud JOIN
user_infos ui
ON ui.id = ud.id
WHERE ui.date_created BETWEEN NOW() - INTERVAL '1 year' AND NOW()
) t
WHERE rownumber <= 10 or id = 1;
If you want them in order, just add order by rownumber as the last statement.
I Have an SQL query giving me X results, I want the query output to have a coulmn called
count making the query somthing like this:
count id section
1 15 7
2 3 2
3 54 1
4 7 4
How can I make this happen?
So in your example, "count" is the derived sequence number? I don't see what pattern is used to determine the count must be 1 for id=15 and 2 for id=3.
count id section
1 15 7
2 3 2
3 54 1
4 7 4
If id contained unique values, and you order by id you could have this:
count id section
1 3 2
2 7 4
3 15 7
4 54 1
Looks to me like mikeY's DSum approach could work. Or you could use a different approach to a ranking query as Allen Browne described at this page
Edit: You could use DCount instead of DSum. I don't know how the speed would compare between the two, but DCount avoids creating a field in the table simply to store a 1 for each row.
DCount("*","YourTableName","id<=" & [id]) AS counter
Whether you go with DCount or DSum, the counter values can include duplicates if the id values are not unique. If id is a primary key, no worries.
I frankly don't understand what it is you want, but if all you want is a sequence number displayed on your form, you can use a control bound to the form's CurrentRecord property. A control with the ControlSource =CurrentRecord will have an always-accurate "record number" that is in sequence, and that will update when the form's Recordsource changes (which may or may not be desirable).
You can then use that number to navigate around the form, if you like.
But this may not be anything like what you're looking for -- I simply can't tell from the question you've posted and the "clarifications" in comments.
The only trick I have seen is if you have a sequential id field, you can create a new field in which the value for each record is 1. Then you do a running sum of that field.
Add to your query
DSum("[New field with 1 in it]","[Table Name]","[ID field]<=" & [ID Field])
as counterthing
That should produce a sequential count in Access which is what I think you want.
HTH.
(Stolen from Rob Mills here:
http://www.access-programmers.co.uk/forums/showthread.php?p=160386)
Alright, I guess this comes close enough to constitute an answer: the following link specifies two approaches: http://www.techrepublic.com/blog/microsoft-office/an-access-query-that-returns-every-nth-record/
The first approach assumes that you have an ID value and uses DCount (similar to #mikeY's solution).
The second approach assumes you're OK creating a VBA function that will run once for EACH record in the recordset, and will need to be manually reset (with some VBA) every time you want to run the count - because it uses a "static" value to run its counter.
As long as you have reasonable numbers (hundreds, not thousands) or records, the second approach looks like the easiest/most powerful to me.
This function can be called from each record if available from a module.
Example: incrementingCounterTimeFlaged(10,[anyField]) should provide your query rows an int incrementing from 0.
'provides incrementing int values 0 to n
'resets to 0 some seconds after first call
Function incrementingCounterTimeFlaged(resetAfterSeconds As Integer,anyfield as variant) As Integer
Static resetAt As Date
Static i As Integer
'if reset date < now() set the flag and return 0
If DateDiff("s", resetAt, Now()) > 0 Then
resetAt = DateAdd("s", resetAfterSeconds, Now())
i = 0
incrementingCounterTimeFlaged = i
'if reset date > now increments and returns
Else
i = i + 1
incrementingCounterTimeFlaged = i
End If
End Function
autoincrement in SQL
SELECT (Select COUNT(*) FROM table A where A.id<=b.id),B.id,B.Section FROM table AS B ORDER BY B.ID Asc
You can use ROW_NUMBER() which is in SQL Server 2008
SELECT ROW_NUMBER() OVER (ORDER By ID DESC) RowNum,
ID,
Section
FROM myTable
Then RowNum displays sequence of row numbers.
I have a process that needs to select rows from a Table (queued items) each row has a quantity column and I need to select rows where the quantities add to a specific multiple. The mulitple is the order of between around 4, 8, 10 (but could in theory be any multiple. (odd or even)
Any suggestions on how to select rows where the sum of a field is of a specified multiple?
My first thought would be to use some kind of MOD function which I believe in SQL server is the % sign. So the criteria would be something like this
WHERE MyField % 4 = 0 OR MyField % 8 = 0
It might not be that fast so another way might be to make a temp table containing say 100 values of the X times table (where X is the multiple you are looking for) and join on that