I have a table which captures backup file sizes and creation dates. It is my hope that I can track down which backup files are growing at a faster rate than others. How can I setup a query to add a column to track the percentage growth or rate of growth?
Example data:
Filename CreationDate Size
DB1 2017-06-19 13:00:28.450 96480
DB1 2017-06-20 13:00:36.627 97568
DB2 2017-06-18 22:00:00.800 19672
DB2 2017-06-19 22:00:00.370 19672
DB2 2017-06-20 22:00:00.913 19672
DB3 2017-06-18 22:00:04.520 17872840
DB3 2017-06-19 22:00:05.183 17873864
DB3 2017-06-20 22:00:06.400 17878984
Edit: I would like to have 2 separate new columns which track the percentage change. Column1 will be the percentage change since the most recent (i.e. change between yesterday and today). Column2 will be the percentage change cine the oldest file on record (i.e. change between today and the oldest date for the specific filename). Hope that helps. Also not sure why I got downvoted for this question.
tSQL... assuming SQL server. You have window functions available that can look ahead at the next record in the partition(filename) allowing you to do the percentages in a query.
SELECT td.fileName
, td.creationdate
, td.size
, lag(td.size) over (partition by td.filename order by td.creationdate asc) / td.size as PercentChange
FROM TableData td
The "magic" is here: lag(td.size) over (partition by td.filename order by td.creationdate asc)
This basically says return the size of the record having the same filename as this one but a creationdate before the record being evaluated.
Using this we can get the prior value if one exists. and then do some basic math. I wasn't sure how you wanted to do the % if it's New size / old or something else... Note if size is an integer we may have integer math involved so you may have to cast size to a decimal value of sufficient size (if you need the decimals)
Related
I've got a problem in my database, understanding a generic Transaction if its a Bet or Win. Currently it consists both in one transaction.
I've an additional field which can help -> Bet Amount, which is constant.
Here is how the table looks like:
Basically what you see in Amount Field in the first transaction, is the Amount the customer starts with. Whenever the amount of next transactions are higher compare to its previous transaction then the specific Bet has got a Win too, if its lower then its only a Bet.
My need is to create an ETL process which will Create this Table:
Hope you can help me write an efficient SQL Server code in order to create the requested Table.
Thanks in advance,
I'm not sure I'd try to do this purely in SSIS, but here's a query that should do the right thing:
select *,
case
when LAG(Amount, 1, Amount) over (order by TransactionID) = Amount then 'Bet'
else 'Win'
end
from dbo.Transactions;
I'm using the LAG() function to look back one row at the value for the Amount column in the previous row (where "previous" is defined by the ordering of TransactionID†). If that value is the same, consider it a Bet otherwise it's a Win.
† It seems like you'd want to consider games in isolation. If that's the case, change the OVER() clause on the LAG() function to partition by GameID order by TransactionID.
Use the script below as SQL Command in your OLEDB Source
SELECT TransactionID, DateTime, GameID, CASE WHEN ISNULL(Amount, '') = '' THEN
'StartGame' WHEN Amount > BetAmount THEN 'win' ELSE 'bet' END AS
TransactionTypeID, BetAmount, Amount
FROM [your table name]
I'm trying to rank a series of transactions, however my source data does not capture the time of a transaction which can happen multiple times a day, the only other field I can use is a timestamp field - will this be ranked correctly?
Here's the code
SELECT [LT].[StockCode]
, [LT].[Warehouse]
, [LT].[Lot]
, [LT].[Bin]
, [LT].[TrnDate]
, [LT].[TrnQuantity]
, [LT].[TimeStamp]
, LotRanking = Rank() Over (Partition By [LT].[Warehouse],[LT].[StockCode],[LT].[Lot] Order By [LT].[TrnDate] Desc, [LT].[TimeStamp] Desc)
From [LotTransactions] [LT]
Results being returned are as below
StockCode |Warehouse |Lot |Bin |TrnDate |TrnQuantity |TimeStamp |LotRanking
2090 |CB |3036 |CB |2016-02-16 00:00:00.000 |2.000000 |0x0000000000500AB9 |1
2090 |CB |3036 |CB |2016-02-16 00:00:00.000 |2.000000 |0x0000000000500A4E |2
First, you should be using rowversion rather than timestamp for keeping track of row versioning information. I believe timestamp is deprecated. At the very least, the documentation explicitly suggests [rowversion][1].
Second, I would strongly recommend that you add an identity column to the table. This will provide the information that you really need -- as well as a nice unique key for the table.
In general, a timestamp or rowversion is used just to determine whether or not a row has changed -- not to determine the ordering. But, based on this description, what you are doing might be correct:
Each database has a counter that is incremented for each insert or
update operation that is performed on a table that contains a
timestamp column within the database. This counter is the database
timestamp. This tracks a relative time within a database, not an
actual time that can be associated with a clock. A table can have only
one timestamp column. Every time that a row with a timestamp column is
modified or inserted, the incremented database timestamp value is
inserted in the timestamp column.
I would caution that this might not be safe. Instead, it gives a reason why such an approach might make sense. Let me repeat the recommendation: add an identity column, so you are correctly adding this information, at least for the future.
You can use something like this to get datetime of transaction:
SELECT LEFT(CONVERT(nvarchar(50),[LT].[TrnDate],121),10) + RIGHT(CONVERT(nvarchar(50),CAST([LT].[TimeStamp] as datetime),121),13)
For first string it will be:
2016-02-16 04:51:25.417
And use this for ranking.
I have a view that may contain more than one row, looking like this:
[rate] | [vendorID]
8374 1234
6523 4321
5234 9374
In a SPROC, I need to set a param equal to the value of the first column from the first row of the view. something like this:
DECLARE #rate int;
SET #rate = (select top 1 rate from vendor_view where vendorID = 123)
SELECT #rate
But this ALWAYS returns the LAST row of the view.
In fact, if I simply run the subselect by itself, I only get the last row.
With 3 rows in the view, TOP 2 returns the FIRST and THIRD rows in order. With 4 rows, it's returning the top 3 in order. Yet still top 1 is returning the last.
DERP?!?
This works..
DECLARE #rate int;
CREATE TABLE #temp (vRate int)
INSERT INTO #temp (vRate) (select rate from vendor_view where vendorID = 123)
SET #rate = (select top 1 vRate from #temp)
SELECT #rate
DROP TABLE #temp
.. but can someone tell me why the first behaves so fudgely and how to do what I want? As explained in the comments, there is no meaningful column by which I can do an order by. Can I force the order in which rows are inserted to be the order in which they are returned?
[EDIT] I've also noticed that: select top 1 rate from ([view definition select]) also returns the correct values time and again.[/EDIT]
That is by design.
If you don't specify how the query should be sorted, the database is free to return the records in any order that is convenient. There is no natural order for a table that is used as default sort order.
What the order will actually be depends on how the query is planned, so you can't even rely on the same query giving a consistent result over time, as the database will gather statistics about the data and may change how the query is planned based on that.
To get the record that you expect, you simply have to specify how you want them sorted, for example:
select top 1 rate
from vendor_view
where vendorID = 123
order by rate
I ran into this problem on a query that had worked for years. We upgraded SQL Server and all of a sudden, an unordered select top 1 was not returning the final record in a table. We simply added an order by to the select.
My understanding is that SQL Server normally will generally provide you the results based on the clustered index if no order by is provided OR off of whatever index is picked by the engine. But, this is not a guarantee of a certain order.
If you don't have something to order off of, you need to add it. Either add a date inserted column and default it to GETDATE() or add an identity column. It won't help you historically, but it addresses the issue going forward.
While it doesn't necessarily make sense that the results of the query should be consistent, in this particular instance they are so we decided to leave it 'as is'. Ultimately it would be best to add a column, but this was not an option. The application this belongs to is slated to be discontinued sometime soon and the database server will not be upgraded from SQL 2005. I don't necessarily like this outcome, but it is what it is: until it breaks it shall not be fixed. :-x
INTRODUCTION TO DATABASE TABLE BEING USED -
I am working on a “Stock Market Prices” based Database Table. My table has got the data for the following FIELDS –
ID
SYMBOL
OPEN
HIGH
LOW
CLOSE
VOLUME
VOLUME CHANGE
VOLUME CHANGE %
OPEN_INT
SECTOR
TIMESTAMP
New data gets added to the table daily “Monday to Friday”, based on the stock market price changes for that day. The current requirement is based on the VOLUME field, which shows the volume traded for a particular stock on daily basis.
REQUIREMENT –
To get the Average and Total Volume for last 10,15 and 30 Days respectively.
METHOD USED CURRENTLY -
I created these 9 SEPARATE QUERIES in order to get my desired results –
First I have created these 3 queries to take out the most recent last 10,15 and 30 dates from the current table:
qryLast10DaysStored
qryLast15DaysStored
qryLast30DaysStored
Then I have created these 3 queries for getting the respective AVERAGES:
qrySymbolAvgVolume10Days
qrySymbolAvgVolume15Days
qrySymbolAvgVolume30Days
And then I have created these 3 queries for getting the respective TOTALS:
qrySymbolTotalVolume10Days
qrySymbolTotalVolume15Days
qrySymbolTotalVolume30Days
PROBLEM BEING FACED WITH CURRENT METHOD -
Now, my problem is that I have ended up having these so many different queries, whereas I wanted to get the output into One Single Query, as shown in the Snapshot of the Excel Sheet:
http://i49.tinypic.com/256tgcp.png
SOLUTION NEEDED -
Is there some way by which I can get these required fields into ONE SINGLE QUERY, so that I do not have to look into multiple places for the required fields? Can someone please tell me how to get all these separate queries into one -
A) Either by taking out or moving the results from these separate individual queries to one.
B) Or by making a new query which calculates all these fields within itself, so that these separate individual queries are no longer needed. This would be a better solution I think.
One Clarification about Dates –
Some friend might think why I used the method of using Top 10,15 and 30 for getting the last 10,15 and 30 Date Values. Why not I just used the PC Date for getting these values? Or used something like -
("VOLUME","tbl-B", "TimeStamp BETWEEN Date() - 10 AND Date()")
The answer is that I require my query to "Read" the date from the "TIMESTAMP" Field, and then perform its calculations accordingly for LAST / MOST RECENT "10 days, 15 days, 30 days” FOR WHICH THE DATA IS AVAILABLE IN THE TABLE, WITHOUT BOTHERING WHAT THE CURRENT DATE IS. It should not depend upon the current date in any way.
If there is any better method or more efficient way to create these queries, then please enlighten.
You have separate queries to compute 10DayTotalVolume and 10DayAvgVolume. I suspect you can compute both in one query, qry10DayVolumes.
SELECT
b.SYMBOL,
Sum(b.VOLUME) AS 10DayTotalVolume,
Avg(b.VOLUME) AS 10DayAvgVolume
FROM
[tbl-B] AS b INNER JOIN
qryLast10DaysStored AS q
ON b.TIMESTAMP = q.TIMESTAMP
GROUP BY b.SYMBOL;
However, that makes me wonder whether 10DayAvgVolume can ever be anything other than 10DayTotalVolume / 10
Similar considerations apply to the 15 and 30 day values.
Ultimately, I think you want something based on a starting point like this:
SELECT
q10.SYMBOL,
q10.[10DayTotalVolume],
q10.[10DayAvgVolume],
q15.[15DayTotalVolume],
q15.[15DayAvgVolume],
q30.[30DayTotalVolume],
q30.[30DayAvgVolume]
FROM
(qry10DayVolumes AS q10
INNER JOIN qry15DayVolumes AS q15
ON q10.SYMBOL = q15.SYMBOL)
INNER JOIN qry30DayVolumes AS q30
ON q10.SYMBOL = q30.SYMBOL;
That assumes you have created qry15DayVolumes and qry30DayVolumes following the approach I suggested for qry10DayVolumes.
If you want to cut down the number of queries, you could use subqueries for each of the qry??DayVolumes saved queries, but try it this way first to make sure the logic is correct.
In that second query above, there can be a problem due to field names which start with digits. Enclose those names in square brackets or re-alias them in qry10DayVolumes, qry15DayVolumes, and qry30DayVolumes using alias names which begin with letters instead of digits.
I tested the query as written above with the "2nd Upload.mdb" you uploaded, and it ran without error from Access 2007. Here is the first row of the result set from that query:
SYMBOL 10DayTotalVolume 10DayAvgVolume 15DayTotalVolume 15DayAvgVolume 30DayTotalVolume 30DayAvgVolume
ACC-1 42909 4290.9 54892 3659.46666666667 89669 2988.96666666667
Access doesn't support most advanced SQL syntax and clauses, so this is a bit of a hack, but it works, and is fast on your small sample. You're basically running 3 queries but the Union clauses allow you to combine into one:
select
Symbol,
sum([10DayTotalVol]) as 10DayTotalV,
sum([10DayAvgVol]) as 10DayAvgV,
sum([15DayTotalVol]) as 15DayTotalV,
sum([15DayAvgVol]) as 15DayAvgV,
sum([30DayTotalVol]) as 30DayTotalV,
sum([30DayAvgVol]) as 30DayAvgV
from (
select
Symbol,
sum(volume) as 10DayTotalVol, avg(volume) as 10DayAvgVol,
0 as 15DayTotalVol, 0 as 15DayAvgVol,
0 as 30DayTotalVol, 0 as 30DayAvgVol
from
[tbl-b]
where
timestamp >= (select min(ts) from (select distinct top 10 timestamp as ts from [tbl-b] order by timestamp desc ))
group by
Symbol
UNION
select
Symbol,
0, 0,
sum(volume), avg(volume),
0, 0
from
[tbl-b]
where
timestamp >= (select min(ts) from (select distinct top 15 timestamp as ts from [tbl-b] order by timestamp desc ))
group by
Symbol
UNION
select
Symbol,
0, 0,
0, 0,
sum(volume), avg(volume)
from
[tbl-b]
where
timestamp >= (select min(ts) from (select distinct top 30 timestamp as ts from [tbl-b] order by timestamp desc ))
group by
Symbol
) s
group by
Symbol
Is there a way in MS access to return a dataset between a specific index?
So lets say my dataset is:
rank | first_name | age
1 Max 23
2 Bob 40
3 Sid 25
4 Billy 18
5 Sally 19
But I only want to return those records between 'rank' 2 and 4, so my results set is Bob, Sid and Billy? However, Rank is not part of the table, and this should be generated when the query is run. Why don't I use an autogenerated number, because if a record is deleted, this will be inconsistent, and what if I wanted the results in reverse!
This obviously very simple, and the reason I ask is because I am working on a product catalogue and I am looking for a more efficient way of paging through the returned dataset, so if I only return 1 page worth of data from the database this is obviously going to be quicker then return a complete set of 3000 records and then having to subselect from that set!
Thanks R.
Original suggestion:
SELECT * from table where rank BETWEEN 2 and 4;
Modified after comment, that rank is not existing in structure:
Select top 100 * from table;
And if you want to choose subsequent results, you can choose the ID of the last record from the first query, say it was ID 101, and use a WHERE clause to get the next 100;
Select top 100 * from table where ID > 100;
But these won't give you what you're looking for either, I bet.
How are you calculating rank? I assume you are basing it on some data in another dataset somewhere. If so, create a function, do a table join, or do something that can calculate rank based on values in other table(s), then you can do queries based on the rank() function.
For example:
select *
from table
where rank() between 2 and 4
If you are not calculating rank based on some data somewhere, there really isn't a way to write this query, and you might as well be returning three random rows from the table.
I think you need to use a correlated subquery to calculate the rank on the fly e.g. I'm guessing the rank is based on name:
SELECT T1.first_name, T1.age,
(
SELECT COUNT(*) + 1
FROM MyTable AS T2
WHERE T1.first_name > T2.first_name
) AS rank
FROM MyTable AS T1;
The bad news is the Access data engine is poorly optimized for this kind of query; in my experience, performace will start to noticeably degrade beyond a few hundred rows.
If it is not possible to maintain the rank on the db side of the house (e.g. high insertion environment) consider doing the paging on the client side. For example, an ADO classic recordset object has properties to support paging (PageCount, PageSize, AbsolutePage, etc), something for which DAO recordsets (being of an older vintage) have no support.
As always, you'll have to perform your own timings but I suspect that when there are, say, 10K rows you will find it faster to take on the overhead of fetching all the rows to an ADO recordset then finding the page (then perhaps fabricate smaller ADO recordset consisting of just that page's worth of rows) than it is to perform a correlated subquery to only fetch the number of rows for the page.
Unfortunately the LIMIT keyword isn't available in MS Access -- that's what is used in MySQL for a multi-page presentation. If you can write an order key into the results table, then you can use it something like this:
SELECT TOP 25 MyOrder, Etc FROM Table1 WHERE MyOrder in
(SELECT TOP 55 MyOrder FROM Table1 ORDER BY MyOrder DESC)
ORDER BY MyOrder ASCENDING
If I understand you correctly, there is ionly first_name and age columns in your table. If this is the case, then there is no way to return Bob, Sid, and Billy with a single query. Unless you do something like
SELECT * FROM Table
WHERE FirstName = 'Bob'
OR FirstName = 'Sid'
OR FirstName = 'Billy'
But I think that this is not what you are looking for.
This is because SQL databases make no guarantee as to the order that the data will come out of the database unless you specify an ORDER BY clause. It will usually come out in the same order it was added, but there are no guarantees, and once you get a lot of rows in your table, there's a reasonably high probability that they won't come out in the order you put them in.
As a side note, you should probably add a "rank" column (this column is usually called id) to your table, and make it an auto incrementing integer (see Access documentation), so that you can do the query mentioned by Sev. It's also important to have a primary key so that you can be certain which rows are being updated when you are running an update query, or which rows are being deleted when you run a delete query. For example, if you had 2 people named Max, and they were both 23, how you delete 1 row without deleting the other. If you had another auto incrementing unique column in there, you could specify the unique ID in your query to delete only one.
[ADDITION]
Upon reading your comment, If you add an autoincrement field, and want to read 3 rows, and you know the ID of the first row you want to read, then you can use "TOP" to read 3 rows.
Assuming your data looks like this
ID | first_name | age
1 Max 23
2 Bob 40
6 Sid 25
8 Billy 18
15 Sally 19
You can wuery Bob, Sid and Billy with the following QUERY.
SELECT TOP 3 FirstName, Age
From Table
WHERE ID >= 2
ORDER BY ID