Imagine you have a website which lists available hotel rooms and their prices.
The hotel owners set a price per day for each room - it only needs to be as complicated as "Jan 1st costs $100" not "Jan 1st 1999 costs $50, Jan 1st 2000 costs $100".
The granularity is limited to day-rate.
What would be the most efficient (in terms of load when querying for rooms) way to represent this in a database?
For each room, have a separate table holding a date field and a price field? ie 365 entries per room.
I see ways to solve this, but the problem becomes slightly more complicated when for example a user wishes to do a query such as "7 days in august with a budget of $500". This is a feature I would dearly like to implement.
The UI will allow owners to set room prices as blocks of time rather than individual day rates - eg if a room price was $50 for jan-jun and $100 for jul-dec then that is two price blocks. Obviously if needs be that could be translated into 365 date type fields, but a solution using two daterange type fields instead would be preferable.
Any pointers as to where I could learn techniques for this would be greatly appreciated. I have searched google and found information on Calendar Tables, but any additional tips or info would be appreciated.
Historically I have used MySQL, but anything would be considered.
In the terminology of Ralph Kimball, this is called a slowly changing dimension.
I would suggest that you look at one of this books. The latest edition of "The Data Warehouse Toolkit" should cover this topic quite well.
Related
I'm racking my brain how to use the Wikipedia API to get a list of the power plants in https://en.wikipedia.org/wiki/Category:Coal-fired_power_stations_in_the_United_States_by_state
Then include the data from the Commission Date field next to each plant. (Alternatively, cross-reference with the "energy infrastructure completed in 19XX" category)
Where do I start? EIA this information, but only for the actual generators that are still in use, not the date for the powerplants housing those generators. I also found some Data related to Co2 production, but those dates go back only to 1945.
Any help would be greatly appreciated!
I have a 2 access 2007 tables with the following fields:
Table 1: Loan Release Table
ReleaseDate as Date
Maturity as Date
MemberName as Text
MemberNo as Text
Term (in months) as Number
Mode (M/Q/Semi-Monthly) as Text
LoanType as Text
LoanAmount as Currency
LoanCode as Text
Table 2: Payments Table
ReceiptNo as Text
DatePaid as Date
MemberName as Text
MemberNo as Text
LoanCode as Text
LoanReceivable as Currency
InterestPaid as Currency
I would like to ask on how to use Query to create a temporary table that will display Members that should pay on current date or a specified date base on their Term, Mode of Payment and Loan Type (Regular Loans every 30 days to pay, Special Loans every 45 days to pay) and their remaining balance.
Here's my First Attempted Query: I tried to subtract 30 days from Current Date and it obviously gave me just the transactions last month. I would like it to list all transactions including those for example Member with Regular Loan 12 month term on their 3rd monthly payment, Member with Special Loan that is due today.
I am thinking of creating another table that contains the schedule of payments of every Loan released and then go from there.
Is there another way than this? Like a Query that can be run everyday without the need for a bulky ScheduleOfPayments table?
I'm an office clerk who 'graduated' from Excel and a novice using Access at worst and I'm not afraid of VBA codes if that is necessary.
If you know of a better way of doing this, please do tell me or point me in the right direction. I'm all for learning new things and having read and learned a lot from stackoverflow before, I am sure that with your help, my question is as good as solved.
Thank you guys for reading my inquiry.
You have here two solutions:
You can write a procedure that will, when needed, calculate\generate a matrix containing payment schedule for each loan and compare it to payment done.
You can write a procedure that will, when a loan is created, generate corresponding records in a payment schedule table. further comparison will be done between the ScheduledPayment table and the Payment table.
So basically you have to manage a similar set of data, either as a calculated/on the fly matrix or as a permanent set of data kept in a table.
The second version is by very very far the most effective one. You think of it as bulky but it is exactly the opposite, and indeed what is done every time you get a loan from a bank, where your banker will let you sign the reimbursement schedule.
The table solution will allow you to make use of all querying facilities, while the calculated solution will force you to write specific procedures each time you'll want to do some data mining. Just think about a question like "What are the expected reimbursements for the month of April 2014?". Answering this question with the ScheduledPayment table will be as easy as getting a cafe out of your nespresso machine. The same answer without the ScheduledPayment table will be like having to do the whole coffee production process before getting your cup ready.
I have a table that holds data for a person who is on a project. The table has a Start date field a nullable End date field. So, a person is on a project from Start to End.
At the moment, they are always billable to the project. But I now have a new requirement that, for a period, they can be non-billable, yet, still working on the project. So, they have been assigned to the project, and are working, but for some reason, the client isn't billed for part of the period they are assigned, or maybe billed at a lower rate.
My idea is to have an exclusion type table, linked to the person assignment table which would have a start date, and end date, and a Rate column, which could be set to zero for no-charge, or else, works as an override value for a period.
Does this seem like valid design? As the person is billed 95% of the time, and probably will never had any exclusion, it makes more sense to me to have an exclusion table.
If anyone has an idea of how to do this better, it would be great.
At the moment, I also have a 'calendar' table, which I join to based on the start/end date of the person's schedule to get the daily rate. So, I could then join to the exclusion date as well, to see if there is an override of the rate?
Issues I might find with my design, are a lot of the joins are based on:
ON DateValue BETWEEN Start AND End
And I am not sure they're the most efficient joins.
If the exception could be one or more period of times (one-to-many) for one project then your design using an exclusion table is the best design.
Example:
June 1, 2013 to June 30, 2013
Exclusion:
June 9, 2013 - 0 Rate
June 25 to 27 - 30% of Original Rate
However, if the exclusion is possible and can only be a maximum of ONE single period (or one-to-one type of relationship) then you might instead put it on the same fields as other fields on project table.
Example:
June 1, 2013 to June 30, 2013
Exclusion:
June 9, 2013 - 0 Rate
I would use this "exclusion" table as single storage for person-project occupation data. In case when person is assigned to project one time without changes in rate, you will have one record in this table. In other cases you will have a history of rate changes in this table.
It looks like your are allowing discount on standard rate to the customer for specific period. for such case, you can set the rate to be negative eg.-$100/hours for the duration to set resource rate for free in your discount/exclusion table. you can find the final rate for that resource for particular period by adding your discount amount and standard amount to get net amount. In your design, you have already mentioned the relation will be made between exclusion and person assignment table. your design will allow to show what discount has been given to the customer. This approach is ok when your are adjusting the billing for exception cases.
In case, your are trying to do correction in project billing, IMO, you should have separate entries in person assignment table for each rate with the duration.
While generating Invoice to the customer, you can show adjusted discounted rate or new revised billing based on the correction.
I have searched and searched but to no avail... has anybody created a payroll module for a U.S. based company? It seems that most of what I've seen is that companies are using payroll companies to process their payroll, but I haven't found anybody using OpenERP 7 for hourly employees with the U.S. tax system (it's not a flat tax rate).
It seems like what I may have to do, is create tax table in PostgresQL for federal, state, and local taxes, then reference those tables in the deduction calculation. I read one article on using the vendors/ or suppliers module and implementing a tax structure from that, but then again, those are still flat rates. I have to believe someone else has done this for the U.S. payroll system, and probably done it better than I could as I am fairly new to OpenERP.
I am in the process of doing something similar for LedgerSMB. The thing is that doing this on an open source model is extremely painful business-model-wise. I am working on solutions to that part but that's outside the scope of your question.
In general many US taxes are set up in marginal rates with certain minimums and maximums. For example income tax withholding is a set of marginal rates within tax brackets. Same with FICA and FUMA, but FICA taxes are capped at a certain level, so a simple tax table with rates, minimums, maximums, etc. and then a way of handling deductions to determine the correct line may be sufficient.
But users of most open source ERP's use third party services for payroll.
I have worked in an ERP. How we did is just calculate the FIT in yearly for all the employee and subtract the withholding amount with multiples.
FIT => Taxable Wages Yearly - (No.of withholding(Exemption))
Do the process as per the revision based on single or married only for annually. No need to update all the tables.
Then,
Divided it based on the frequency from the employee table information
EX:
for monthly : FIT/12
for daily : FIT/365
For SIT you have to use based on the document in the state usine case function.
I can't figure it out! (CustomRollUpColumn??, or some custom made MDX calculated thing)
My problem: I have a dimension TypeOfRow who's function it is to display the ... well yes ... type of row. I'm working in the financial sector and, always, need to provide the ultimate result ==>> The Total Contribution. I read, amongst others, the article of Martin Mason ( http://martinmason.wordpress.com/2012/02/26/the-ssas-financial-cubepart-1ragged-hierarchies/ ) and designed the dimension as a "Naturalized Parent-Child Hierarchy".
The dimension, 5 levels, I designed for this solution is (simplyfied):
•+/+ Revenue (several types of)
•-/- Cost (several types of)
•= Total Contribution
A user requirement is that the "Total Contribution" always display the "Total Contribution" even if any the Revenue- or Cost types are filtered out.
My question: is this possible showing the total of a dimension without showing all the members (in Excel but I hope to configure this in SSAS 2008R2)?
many thanks in advance, - Leon