I am creating a SQL Server database that will be used in a web api for both a web application and mobile.
I've always used lookup tables (example: Category Lookup Table) and referenced the IDs (Product Table with CategoryID)
I don't know if I'm doing this using old methods.
Categories (Lookup Table)
---------
CategoryID
CategoryName
SubCategories (Lookup Table)
----------
SubCategoryID
SubCategoryName
CategoryID
Products
--------
SubCategoryID
ProductName
.....
My question is, is this still the proper way? Or do I skip the lookup table and call out the SubCategory directly?
Products
------
SubCategoryName
ProductName
Any advice is greatly appreciated.
You can do it in tow ways
1.
Categories (Lookup Table)
CategoryID
CategoryName
SubCategories (Lookup Table)
SubCategoryID
SubCategoryName
CategoryID
Products
ProductName
CategoryID
SubCategoryID
link both id's with foreign keys, it is normalized way
Answer of your question is here.
if you want more waster way you can approach denormalized structure.
Categories (Lookup Table)
CategoryID
CategoryName
SubCategories (Lookup Table)
SubCategoryID
SubCategoryName
CategoryID
Products
ProductName
Categoryname
SubCategoryname
create an insert/update trigger on Products table to make sure the Categoryname/subCategoryname are valid.Data consistency will be maintained.
You will get faster data from this approach.
Related
I am creating a SQL Server database and I have a question about one relation. I have the two entities Product and Category. The relation is one to many, so one product can have one category, but one category can have many products.
Which way is normalized and why (which normalization form)?:
Product { productId, productName, productPrice }
Category { categoryId, Name }
Product { productId, productName, productPrice, categoryName }
If Category has more attributes and not only name I would make another table without doubt. But in this case I am not sure whether I have to make new table since it contains only name or leave it as varchar column. Isn't that going to create a lot more columns and take more space in database?
I think you should create the following two tables:
1. Category { categoryId, Name }
2. Product { productId, categoryId, productName, productPrice }
Considering that the categoryId in category table is a Primary Key, you should creata a foreign key constraint on categoryId in the Products table referencing to categoryId in the category table.
I'm not a DBA and I don't know what is the best solution. I have two tables,
Custumers Table
CustomerId (primary key, identity)
...
and
Suppliers Table
SupplierId (primary key, identity)
...
and I want to store multiple telephone number and multiple emails. I thought to create two other tables, Emails and Telephones and use those in join with my Custumers and Suppliers, something like
Telephones Table
Id
UserId (reference to SuppliersId or CustomerId)
Value
...
But if I use as key for custumers and suppliers an Identity I'll have for sure problems. I'm thinking to do something like
Telephones Table
Id
SuppliersId
CustumersId
Value
...
But I don't know if is a good design. Any advice?
Thank you
One idea:
Entity (ID (PK), {common fields})
Customer (ID (PK), EntityID (FK), {other fields})
Supplier (ID (PK), EntityID (FK), {other fields})
Telephone (ID (PK), EntityID (FK), Value)
This also has the added advantage of reducing duplication between Customer and Supplier.
A good design would be
Customers: Table of customers - CustomerId, Other columns
Suppliers: Table of suppliers - SupplierId, Other columns
Telephones: Table of telephones - TelephoneId, other columns
CustomerTelephones: CustomerId, TelephoneId
SupplierTelephones: SupplierId, TelephoneId
my advise is that you assign an ID for the table then add a reference field with the same datatype with the SupplierID and CustomerID
The other answers are decent beginner solutions, but they all have the same fundamental flaw in that Customer or Supplier are Relationships and not their own unique entities. A Customer is not a person, it's a relationship between you and a person.
In fact a person could be an Employee, Customer, Supplier all at the same time, or over time.
A Customer or Supplier could also be a Business, with many involved people.
Here is the correct answer:
PARTY
id
type {individual, organization, automated_agent}
org_name null
first_name null
last_name null
PARTY_RELATIONSHIP
from_party_id FK PARTY
type {supplier_of, customer_of, ...}
to_party_id FK PARTY
from_date
to_date null
Usage:
Insert into party (id, type, org_name) values (1, 'organization', 'Raw Steel Co');
Insert into party (id, type, f_name, last_name) values (2, 'individual', 'Davide', 'X');
-- Raw Steel Co is both a customer of and supplier to you:
Insert into party_relationship values (1, 'supplier_of', 2, getdate(), null);
Insert into party_relationship values (1, 'customer_of', 2, getdate(), null);
Now, some people don't like Single Table Inheritance because of the nulls, but goddam it is easier to work with. Use Class Table Inheritance if you're finicky.
The 'type' columns should be foreign keys to type tables.
you can do like
Customers: Table of customers - CustomerId, Other columns
Suppliers: Table of suppliers - SupplierId, Other columns
Telephones: Table of telephones - TelephoneId,TypeId,TypeName, other columns
where TypeName will be Customers or Suppliers, ant TypeId will be id of the resp.
I have a table that contains all products. There are 3 distinct types of products so these have their own tables, lets say ProductType1, ProductType2, ProductType3.
There is a 1-1 relationship between Products and ProductType(n) on ProductId, but to further constraint the child tables there is an additional relationship using a ProductId, ProductTypeId in Products, and a ProductId, ComputedProductTypeId in each of the other tables.
This ensures that a product can only be added to a single matching ProductType table.
The question is this. As there is already a relationship between the 2 tables on ProductId, rather than using an index for the FK, can I get away with a unique key to constrain the relationship, or will this cause performance issues?
Products
PK ProductId
FK ProductId, ProductTypeId
^
*Add an index for this or unique key constraint?*
ProductType(n)
PK ProductId
FK ProductID, ComputedProductTypeId (fixed int)
Creating an index will be better approach.
If you want to delete entries from your master table, SQL server looks for FK relations if any exists. So Creating Index on your composite key (which includes FK) will speed up the process.
im developing a simple access application that helps us to order the right products for a project. i have a table for each contractor containing its products. i have a table "favorite-products" that relates to products and gives additional information how and when they should be used.
normally id have a big table (containing all products) that has a contractor-column. i my favorite-products table i could then easyly relate to a product. but here i need to keep the products in separate tables. so whats the best way to connect my favorite-products table with the products in the contractor-tables?
thanks :)
This is not the best design.
You should UNION all contractor tables together and JOIN with the result:
SELECT *
FROM (
SELECT product
FROM contractor1
UNION ALL
SELECT product
FROM contractor2
UNION ALL
…
) c
JOIN favorite f
ON f.product = c.product
You better keep one single table for you products with contractor as a field.
It will be much easier to query and to manage.
I would create a contractors table, a product table and then a many-to-many linked table contractors to products. Also i would create a favorite-products table in which you can also have a many-to-many contractors to products link for those cases where a product can come from more than 1 contractor
So, you'll have a Contractor, Product and Contractor_Product table. Something like (in psuedo-sql):
create table Contractor {
id int primary key,
name varchar(50) not null,
...
}
create table Product {
id int primary key,
name varchar(50) not null,
...
}
create table Contractor_Product {
contractorid int references Contractor(id),
productid int references Product(id),
...,
primary key contractorid, productid
}
Now, I'm not 100% sure what you want from the "Favorites" table. It may not be a table, but rather a query. Or, maybe you want a table that similar to the Contractor_Product table? Or just another "isfavorite bool default=false" column on the Contractor_Product table?
Hope that helps!
I want to store multiple translations of an text in a MSSQL database.
for example one table product with the columns
ProductId
ProductPrice
ProductNameId
primairy key = ProductId
and a table with the productnames
Id
Language
Name
primairy key = Id and Language
How can i create an foreign key to link the Product.ProductNameId to ProductName.Id
I think that the most appropriate pk-fk relationship is between ProductId on the Product table, and a ProductId (without Language) in the ProductName table. The field on the Product table is the pk, and the field in the ProductName table is the fk. That will ensure that there are no records in the PeoductName table that don't match with a record in the ProductName table.
If you want to treat Language similarly, then you can create a Language table with a LanguageId field. then, make a LanguageId field in the ProductNames table, and make that a fk.
when you retrieve product information, you JOIN Product and ProductName on their ProductId fields, and then specify the LanguageId in the WHERE clause.
I'd change the ProductNames table to:
Id
ProductId
Language
Name
With these constraints:
Primary key on Id
Foreign key on ProductId
Unique constraint on (ProductId,Language)