I am very new to Access and I am working on a database and I need help coming up with a solution:
I am recording data from a bunch of asphalt laying crews. Each crew has a record with a field for production and equipment. Each crew has varying types of equipment and varying quantities of equipment. Therefore, I would need to create a new table for the type and quantity of equipment every time I enter a new record... can someone please help me come up with a solution?
You do not need a new table for each record, you just need a properly set up table. Let us say:
Crews table
CrewID
Location
Etc
CrewMembers table
MemberID
Etc
CrewEquipment table
CrewID
EquipmentID
DateIn
DateOut
Etc
Equipment table
EquipmentID
Details
Etc
You might like to read http://r937.com/relational.html
With the above set-up, you can have a Crew form with subforms for members and equipment. You can get an idea from this create form to add records in multiple tables
Creating new table everytime is not solution, you should clear some RDBMS concept like normalization first. Create separate table for
crew member (which include crew member id, his name, salary/wages
List item per hour) equipments (which include equipments id, operation cost per hour etc)
Shift (can be separated by date and shift time etc)
Then create proper relationship between tables and this way you can create proper relational database system. so finish some basic tutorial first then start development.
Related
Let me describe briefly the table structures:
Customer Table
id | name | address_line_one | address_line_two | contact_no_one
SaleInvoice Table
id | id_Customer (Foreign Key) | invoice_no
If I have to print a Sale invoice, I have to use the Customer information (like name, address) from the Customer table.
Assume that after a year, some customer data changes (like name or address), and I update the new data in my customer table. Now, if the customer asks for an old invoice, it will be printed with the new customer data which shall be legally wrong.
Does that mean, I have to create
name_customer
address_line_one_customer
...
and all these fields in the Sale Invoice table too?
If yes, is there a better way to get data from these fields in Customer table to the Sale Invoice table then to write a SQL query to get the values and then set the values?
This is really up to you. In some cases, where it is a legal document, you will save all the details so that you can always bring it up the way it was created. Alternatively if you are producing pdf invoices then save them to be 100% sure.
The other alternative is to create a CustomerHistory table, so that past versions are always saved with a date range, so that you can go back to the old version.
It depends on the use cases, but those are your main options.
It sounds like a problem easily solved by placing the Employee table in version normal form (VNF). This is actually just a flavor of 2nf but done in a way that provides the ability to query current data and past data using the same query.
A datetime parameter is used to provide the distinction. When the value is set to NOW, the current data is returned. When the value is set to a specific datetime value in the past, the data that was current at that date and time is returned.
A brief discussion of the particulars can be found here. That answer also contains links to more information if you think it is something that would work for you.
I'm creating a rather large APEX application which allows managers to go in and record statistics for associates in the company. Currently we have a database in oracle with data from AD which hold all the associates information. Name, Manager, Employee ID, etc.
Now I'm responsible for creating and modeling a table that will house all their stats for each employee. The table I have created has over 90+ columns in it. Some contain data such as:
Documents Processed
Calls Received
Amount of Doc 1 Processed
Amount of Doc 2 Processed
and the list goes on for well over 90 attributes. So here is my question:
When creating this table in my application with so many different columns how would I go about choosing a primary key that's appropriate? Should I link it to our employee table using the employees identification which is unique (each have a associate number)?
Secondly, how can I create these tables (and possibly form) to allow me to associate the statistic I am entering for an individual to the actual individual?
I have ordered two books from amazon on data modeling since I am new to APEX and DBA design. Not a fresh chicken, but new enough to need some guidance. An additional problem I am running into is that each form can have only 60 fields to it. So I had thought about creating tables for different functions out of my 90+ I have.
Thanks
4.2 allows for 200 items per page.
oracle apex component limits
A couple of questions come to mind:
Are you sure that the employee Ids are not recyclable? If these ids are unique and not recycled.. you've found yourself a good primary key.
What do you plan on doing when you decide to add a new metric? Seems like you might have to add a new column to your rather large and likely not normalized table.
I'd recommend a vertical table for your metrics.. you can use oracle's pivot function to make your data appear more like a horizontal table.
If you went this route you would store your employee Id in one column, your metric key in another, and value...
I'd recommend that you create a metric table consisting of a primary key, a metric label, an active indicator, creation timestamp, creation user id, modified timestamp, modified user id.
This metric table will allow you to add new metrics, change the name of the metric, deactivate a metric, and determine who changed what and when.
This would be a much more flexible approach in my opinion. You may also want to think about audit logs.
I've run into a bit of a pickle during my development of a web application. I've boiled down the complexity of the application for sake of simplicity in this question.
The purpose of this web application is to sell insurance. Insurance can be purchased through an agent (Agency) or over the phone directly (Customer). Insurance policies can be paid through the agency or the customer can pay for the policy directly. So money is owed (invoiced) and received (payments) from multiple sources (Agencies/Customers).
Billing Options:
Agency (Agency collects from customer outside of app)
Customer
Here's where it gets complicated. Agencies are stored in a separate database table than customers (for obvious reasons). However, both agencies and customers need to be able to make payments and have invoices assigned to them. I'm having difficulty figuring out how to create the proper database schema to allow for both types of database records to be connected to their invoices and payments.
My initial plan was to set up separate relationship (joining) tables that link the agencies and customers to invoices/payments.
However, now that I've been thinking about the problem more, I think it might be beneficial to merge both agencies and customers into a single "Payee" table which would then be associated with payments/invoices. The payee table would only store a primary key. It would not contain actual names or info for the payee - instead I would pull that data via a JOIN with either the agencies or customers tables.
Regardless of whatever solution I choose I am still faced with the problem when creating a new payment record is that I need to scan both the agencies and customers table for possible payees. I'm wondering if there's a proper way to approach this from a database schema standpoint (or from an accounting/e-commerce standpoint).
What is the correct way to handle this type of situation? All ideas and possible solutions are most welcome!
Update 01:
After a few helpful suggestions (see below) I've come up with a possible solution that may solve this issue while keeping the data normalized.
The one thing about this method that rubs me the wrong way is that I will have to make multiple table selects to get a list of all the people who can potentially make payments and/or have invoices assigned to them.
Perhaps this is unavoidable though in this situation since indeed there are different "types" of people that can be associated with payments and invoices. I'm stuck with a situation where I have two different types of records that need to be associated to the same thing. In the above approach I'm using the FKs to link each table (Agencies/Customers) to a Payee record (the table that unifies both Agencies/Customers) and then ultimately links them to Payments and Invoices.
Is this the proper solution? Or is there something I've overlooked?
There are several options:
You might put this like you'd do it with OOP programming and inheritance.
There is one table Person which holds an uniqueID and a type (Agency, Customer, more in Future). Additionally you might add columns with meta-data like who inserted/when/why and columns for status/soft-delete/???
There are two tables Agency and Customer, both holding a PersonID as FK.
Your Payee is the Person
You might use a schema-bound VIEW with a UNION ALL to return both tables of your modell in one result. A unique index on this view should ensure, that you'll have a unique key, at least as combination of the table-source and the ID there.
You might use a middle table with the table-source and the ID there as unique Key and use this two-column-id in you payment process
For sure there are several more...
My best friend was the first option...
My suggestion would be: instead of Payees table - to have two linking tables:
PayeeInvoices {
Id, --PK
PayeeId,
PayeeType,
InvoiceId --FK to Invoices tabse
}
and
PayeePayments {
Id, --PK
PayeeId,
PayeeType,
PaymentId --FK to Payments table.
}.
PayeeType is an option of two: Customer or Agency. When creating a new payment record you can query PayeeInvoices by InvoiceId to get PayeeType and corresponding PayeeId, and then lookup the rest of the data in corresponding tables.
EDIT:
Having second thoughts now. Instead of two extra tables PayeeInvoices and PayeePayments, you can just have PayeeId and PayeeType columns right in Invocies and Payments tables, assuming that Invoice or Payment belongs only to one Payee (Customer or Agency). Both my solutions are not really normalized, though.
I'm creating this little Access DB, for the HR department to store all data related to all the training sessions that the company organizes for all the employees.
So, I have a Training Session table with information like date, subject, place, observations, trainer, etc, and the unique ID number.
Then there's the Personnel table, with employer ID (which is also the unique table number), names and working department.
So, after that I need another table that keeps a record of all the attendants of each training session. And here's the question, should I use a table for that in the first place? Does it have to be one table for each training session to store the attendants?
I've used excel for quite some time now, but I'm very new to Access and databases (even small ones like this). Any information will be highly appreciated.
Thanks in advance!
It should be one table for persons, one table for trainings, and one for participation/attendance, to minimize (or best: avoid) repetition. Your tables should use primary and foreign keys, so that there are one-to-many relationships between trainings and attendances as well as people and attendances (the attendances table would then have a column referring to the person who attended, and another column referring to the training session).
Google "database normalization" for more detail and variations of that principle (https://en.wikipedia.org/wiki/Database_normalization).
I'm fairly new to this so you may have to bear with me. I'm developing a database for a website with athletics rankings on them and I was curious as to how many tables would be the most efficient way of achieving this.
I currently have 2 tables, a table called 'athletes' which holds the details of all my runners (potentially around 600 people/records) which contains the following fields:
mid (member id - primary key)
firstname
lastname
gender
birthday
nationality
And a second table, 'results', which holds all of their performances and has the following fields:
mid
eid (event id - primary key)
eventdate
eventcategory (road, track, field etc)
eventdescription (100m, 200m, 400m etc)
hours
minutes
seconds
distance
points
location
The second table has around 2000 records in it already and potentially this will quadruple over time, mainly because there are around 30 track events, 10 field, 10 road, cross country, relays, multi-events etc and if there are 600 athletes in my first table, that equates to a large amount of records in my second table.
So what I was wondering is would it be cleaner/more efficient to have multiple tables to separate track, field, cross country etc?
I want to use the database to order peoples results based on their performance. If you would like to understand better what I am trying to emulate, take a look at this website http://thepowerof10.info
Changing the schema won't change the number of results. Even if you split the venue into a separate table, you'll still have one result per participant at each event.
The potential benefit of having a separate venue table would be better normalization. A runner can have many results, and a given venue can have many results on a given date. You won't have to repeat the venue information in every result record.
You'll want to pay attention to indexes. Every table must have a primary key. Add additional indexes for columns you use in WHERE clauses when you select.
Here's a discussion about normalization and what it can mean for you.
PS - Thousands of records won't be an issue. Large databases are on the order of giga- or tera-bytes.
My thought --
Don't break your events table into separate tables for each type (track, field, etc.). You'll have a much easier time querying the data back out if it's all there in the same table.
Otherwise, your two tables look fine -- it's a good start.