I'm currently designing a billing app that can be used for a consultant to bill their customers. I currently have 3 tables in mysql for this the database to store information. The tables are activity, customer and expenses.
In the activity table I've got activity_id, activity_name, percent_rate, hours
In the customer table I've got customer_id, and all the information on the customer
In the expense table I've got expense_id, description, cost, quantity
I'm trying to figure out how to design the database that I can keep track of the hours spent on activity per customer. I want it to be used for multiple customers, but can't figure out how to structure the database for this.
Is it best to use a foreign key like custId in the activity table?
Yes.
But a lot depends on your overall structure. That's a pretty simple data model. If for instance you had something like "project", that the activities are related to, you'd put the customer id in the project table. Then again, if there were multiple customers for that activity, you'd have another table, with activity_id and customer_id in it, just to show that relationship. So, it depends on the problems you're trying to model.
Sounds like it. Does each activity have one (and only one) customer? Then you could have activity_id be the primary key of the activity table, and customer_id be a foreign key. For each customer you can get a list of activities, and for each activity you can figure out the # of hours the consultant worked for that customer on that activity.
Related
I'm trying to implement a flight booking system, and the use case is as follow:
A registered customer should be able to buy several tickets, not only for himself, and for each ticket the passenger info would be recorded.
In the database design, I have two tables -- a ticket table, and a purchase table. Tuples in the ticket table records only information with the flight and the passenger, and each ticket has a unique ticketID as primary key. Inside the purchase table, it has a foreign key reference to the ticket table, and has attributes that indicate which registered use this purchase record belongs to.
Now, suppose I have several tuples of passenger data sent to the server, the first thing I should do is to insert new tickets, and then I could perform insertion on the purchase table indicates the relation between each tickets and the person who bought the tickets. Notice that the new records in the purchase table would have ticket_ids which were just created by new tickets.
My confusion is: how do I implement this within one operation as a whole? ** In the purchase table, I would also give the tuples that are created by the same customer in the same transaction an ID, indicates that those tickets belongs to the same purchase records. ** Could I achieve this using a stored procedure? I feel like the passing of data is tricky, since I'm very new to stored procedure, etc.
I'm running for office and have created a web app for tracking my door knocks to voters at their homes. The database contains a table called voters that contains all the necessary information about voters in my community.
I'd like to add a new feature to track donors to my campaign. Not all of these donors live in the community and do not vote in the district where I'm running for office. I do not need to track the same kind of info for these individuals as I do for the voters so I'm going to place these individuals into a table called nonvoters.
Now, the individuals in my "voters" table can also make donations, and I want to track those as well.
To track the donations from both voters and nonvoters, I'd like to set up a new table called "donations." This table would contain the appropriate details about the donation.
But I'm uncertain as to what the best structure is for linking the donations table to the "voters" and "nonvoters" table. If I create a column called voter_id in the table to key it to the donors information, there's no way to know which table that ID refers to. So do I set up two columns, nonvoter_id and voter_id and insert the ID into the applicable column depending on whether the donor is a voter? This seems weird.
Or maybe I create a column in both the voters and nonvoters table called donor_id that I can use to link my data in the donations table. If I went this route, it seems like I'd have to do a some behind the scenes work to ensure the donor_id was unique and was keyed to the data inside the donations table.
Or maybe there are other approaches I'm not familiar with. Any guidance is appreciated.
I would use a single table for voters and non-voters, let's say persons. You can have a flag in the persons table that indicates if the person is a voter or you may even derive this from their address (if that's possible).
I would create a donations table and link each donation to a person (or persons) in the persons table using the id in the persons table. If a donation can be given by multiple people, then you will need a 3rd connection table with person id and donation id as 2 fields. These 2 fields would be the primary key for the connection table.
I am converting a spreadsheet to a database but how do i accommodate multiple values for a field?
This is a database tracking orders with factories.
Import PO# is the unique key. sometimes 1 order will have 0,1,2,3,4 or more customers requiring that we place their price tickets on the product in the factory. every order is different. what's the proper way to accommodate multiple values in 1 field?
Generally, having multiple values in a field is bad database design. Maybe a one to many relationship will work in this scenario.
So you will have an Order table with PO# as the primary key,
Then you will have a OrderDetails table with the PO# as a foriegn key. i.e. it will not be designated as a primary key.
For each row in the Order table you will have a unique PO# that will not repeat across rows.
In the OrderDetails table you will have a customer per row and because the PO# is not a primary key, it can repeat across rows. This will allow you to designate multiple customers per order. Therefore each row will have its own PriceTicketsOrdered field so you can know per customer what the price is.
Note that each customer can repeat across rows in the OrderDetails table as long as its for a different PO# and/or product.
This is the best I can tell you based on the clarity of your question.
Personally, I normally spend time desinging my database on paper or using some drawing software like visio before I start implementing my database in a specific software like MySql pr PostgreSql.
Reading up on ER Diagrams(Entity Relationship diagrams) might help you.
You should also read up on Database normalization. Probably you should read up on database normalization first.
here is a link that might help:
http://code.tutsplus.com/articles/sql-for-beginners-part-3-database-relationships--net-8561
I'm working on a very simple DB.
Imagine I've table customer and table seller.
The customer is able to request a quotation for some products
There will be a simple form that allow to customers to select products and submit the quotation.
Now, should I create table : "Quotation" and store all quotations (with id_quotation..etc)?
Thank you all
Without knowing all of the business rules that govern the requirements of this database, perhaps the following design will help to answer your question and explain a few concepts in the process.
In database terms, an entity is a person, place, or thing about which we want to collect and store data. From your description we can already see two entities: seller and customer. This is important since the entities we identify conceptually become database tables in their own right.
The seller table should contain data applicable only to sellers. Thus, the qualities (attributes) about sellers that we want to store become columns in our seller table. Each row (record) in the seller table represents an individual seller. Each individual seller is uniquely identified in the seller table with a unique value stored in it's primary key column, which we can name seller_id.
A simplified version of such a table could look like this:
In a similar manner, the customer table should contain data only applicable to customers. The qualities (attributes) about customers that we wish to store become the columns in the customer table. Each row (record) in the customer table represents an individual customer. Each individual customer is uniquely identified in that table with a unique value in it's primary key column, which we can declare as customer_id.
A simplified version of this table:
I'm guessing the business rules state that any customer is able to request any number of products, from any seller, any number of times...since surely any seller would want as many sales and customers as possible!
How can we express and record the interactions (relationship) between seller and customer?
This is done with a new kind of entity: a composite entity. It becomes a new table, having it's own primary key, and contains seller_id and customer_id as foreign keys. The foreign keys in this table connect (relate) the seller table to the customer table.
We can name this new table quotation (if that is your preferred name). Each row of this table is intended to capture and record each and every individual transaction between a customer and a seller. The columns (attributes) of this table are the data that apply to a transaction between a customer and seller, such as amount or date of sale.
A very simplified version of this composite entity:
Note that the foreign key values that exist in this table must already exist in their respective tables as a primary key value. That is, a foreign key value cannot be entered into this table unless it exists already as a primary key value in it's own table. This is important, and it is called referential integrity - it ensures that there is no record of a customer purchasing from a non-existent seller, etc.
In the example above we can see that Builder B requested a quotation from Acme Construction in the amount of $3500.00. They then requested another quotation at another time for the amount of $1800.00. What else does it reveal? All existing customers have ordered something. Acme Lumber has not made a sale at all (yet), etc.
A design such as this enables the database to store any number of transactions between sellers and customers. Likewise, it supports the addition of any number of new customers and sellers, even if they have not sold or purchased anything yet. Queries can be run that reveal which sellers have sold the most or least, and so on.
Good luck with your studies!
I am modeling a database that will hold data relating sales from a shop. I have two different kind of users which have distinct properties.
In my normalization process I created a User1 Table and a User2 Table.
The problem I have is tracking sales. For example if I want to track sales say for a particular kind of user for a product and know the users buying trends for that product, I would have to create two tables, Bread1 and Bread2 for the two types of users.
I came up with a solution but I don't know the performance implications on the long run or if its the best solution at all. The solution is having a unified table User which have the ID's of both users.
If there is any other better solution, I would appreciate it.
Thanks.
Better to have just one table for Users and one for Products and so on. You can easily categorize your users or products by making an another table for grouping them.
UserTypes(UserTypeId PK, ...)
Users(UserId PK, UserTypeId FK, ...)
Also for properties you mentioned for users or even for products, You can have a list of properties in a table and assign them by a third table to users.
Properties(PropertyId PK, Name)
UsersProperties(UserPropertyId PK, UserId FK, PropertyId FK, Value)