I have a table of dentists and services. And I want it to be dynamic so I have added a "add services" function. but how can I normalize it if services are not defined yet? since I didn't add yet.
the solution I've made is that I created a new table which is specialty where it creates new column every time I added a new service. But I dont know if it's very improper to create a new column within the add services function itself. But that's the only way I think. Are there any ways to solve it?
Dynamic columns are not good at all!
Tables should be static to be reliable.
Use relation-tables instead.
Example
You have a dentists table. It has an id column as primary-key.
Create a services table. Of course it should have a primary-key. besides that, put a dentist_id column. This will contain the id of the dentist in the dentists table.
If you provide more information and code or database schema, we maybe able to help more.
EDIT
As ADyson mentioned, if it is possible that multiple dentists work on one service, do a many-to-many relation.
Example
You have a dentists table And a services table. They both have an id column as primary-key.
Create a r_dentist_service table. Of course it should have a primary-key. besides that, put a dentist_id column and a service_id column. These should contain the respective IDs. This table will relate dentists to services.
Related
What is the proper way to give user to use custom attributes ?
As an example
Consider that,
There is a web application, using the frontend user interface admin user need to be able to add custom attributes to the Employee later. Which means not only for specific employee record but also for all employees.
Initially, There is an employee table which has following fields,
| Employee |
|----------|
| ID |
| Name |
| Email |
Later, system admin want to add few custom fields (attribute) to Employee table such as Nationality, Mobile Number, Address.
Is it good idea to alter the table and add new column to it ? or Is there any proper way to do this.
Currently, I am working on the ER diagram of database and hope to use Postgresql or MySQL to implement it.
Thanks !
There are multiple approaches to do what you want:
Add new columns to the given table.
Create a new table with additional attributes.
Use a JSON column in the table to handle flexible new attributes.
Create an entity-attribute-value table, with one row per entity attribute, for the flexible attributes.
How do you choose among these? It depends on factors that you have not discussed in the question. These include:
Do all entities have the same attributes?
Can you take the table offline to change its structure?
How large are the tables and how wide the rows? And are these issues with query performance?
How often will new columns be added?
There may be more considerations, and there may be more possible solutions. The point is that there is no generic right answer. Different solutions have different strengths and weaknesses.
I have few tables to store company information in my database, but I want to focus on two of them. One table, Company, contains CompanyID, which is autoincremented, and some other columns that are irrelevant for now. The problem is that companies use different versions of names (e.g. IBM vs. International Business Machines) and I want/need to store them all for futher use, so I can't keep names in Company table. Therefore I have another table, CompanyName that uses CompanyID as a foreign key (it's one-to-many relation).
Now, I need to import some new companies, and I have names only. Therefore I want to add them to CompanyName table, but create new records in Company table immediately, so I can put right CompanyID in CompanyName table.
Is it possible with one query? How to approach this problem properly? Do I need to go as far as writing VBA procedure to add records one by one?
I searched Stack and other websites, but I didn't find any solution for my problem, and I can't figure it out myself. I guess it could be done with form and subform, but ultimately I want to put all my queries in macro, so data import would be done automatically.
I'm not database expert, so maybe I just designed it badly, but I didn't figure out another way to cleanly store multiple names of the same entity.
The table structure you setup appears to be a good way to do this. But there's not a way to insert records into both tables at the same time. One option is to write two queries to insert records into Company and then CompanyName. After inserting records into Company you will need to create a query that joins from the source table to the Company table joining it on a field that uniquely defines the record beside the autoincrement key. That will allow you to get the key field from Company for use when you insert into CompanyName.
The other option, is to write some VBA code to loop through the source data inserting records into both. The would be preferable since it should be more reliable.
I am trying to figure out what the best way to design this database would be. Currently what I have works, but it requires me to hard-code values where I would like it to be dynamic in the future.
Here is my current database design:
As you can see, for both the Qualities and the PressSettingsSet tables, there are many columns that are hard-coded such as BlownInsert, Blowout, Temperature1, Temperature2, etc.
What I am trying to accomplish is to have these be dynamic. Each job will have these same settings, but I would like to allow the users to define these settings. Would it be best to create a table with just a name field and have a one-to-one relationship to another table with a value for the field and a relation to the Job Number?
I hope this makes sense, any help is appreciated. I can make a database diagram of how I think it should work if that is more helpful to what I am trying to convey. I think that what I have in mind will work, but it just seems like it will be creating a lot of extra rows in the database, so I wanted to see if there is possibly a better way.
Would it be best to create a table with just a name field and have a one-to-one relationship to another table with a value for the field and a relation to the Job Number?
That would be the simplest - you could expand that by adding data-effective fields or de-normalize it by putting it all in one table (with just a name and value field).
Are the values for the settings different per job? If so then yes a "key" table" with the name ans a one-to-many relationship to the value per job would be best.
Ok I am very new to creating databases with Entity in mind.
I have a Master table which is going to have:
departmentID
functionID
processID
procedureID
Each of those ID's need to point to a specific list of information. Which is name, description and owner of course they link back to each ID in the master table.
My question is, should I make 4 separate tables or create one table since the information is the same in all the tables except one.
The procedureID will actually need to have an extra field for documentID to point to a specific document.
Is it possible and a good idea to make one table and add some inheritance, or is it better to make 4 separate tables?
Splitting data into a number of related tables brings many advantages over one single table. Also by having data held in separate tables, it is simple to add records that are not yet needed but may be in the future. You can also create your corresponding objects for each table in your code. Also it would be more difficult to split the data into separate tables in the future if somehow you need to do that.
I'd like to design a cloud business solution with 4 default tables, a user may add a custom field(Column?) or a add a custom object(Table?).
My first thought was to create a new database for each account but there's a limit to database number on a sql server instance,
2nd solution : for each account create a new schema by duplicating the 4 default tables for each schema.
3rd solution : create 4 unique tables with a discriminant column (ACCOUNT_ID), if a user wants a new field add a join table dedictated to that ACCOUNT_ID, if he wants a new object then create a new table.
What are your thoughts? Does any body know how existing cloud solutions store data? (for instance salesforce)
BTW, I don't want to create a VM for each account.
Thanks all for your suggestions, that helped me a lot especially the microsoft article suggested by John.
Since few architectural points are shared between accounts (the 4 default tables are just a suggestion for the user, I expect a full customization), I've opted for the schema per account design with no EAV pattern.