SQL Creating view from 3 tables - sql

Question

I have three tables: Products, Attributes and AttributesDefinitions.
Products:
+----+------+
| Id | Name |
+----+------+
| 1 | Shoe1|
+----+------+
| 2 | Shoe2|
+----+------+
| 3 | Shoe3|
+----+------+
AttributesDefinition:
+----+---------+
| Id | Name |
+----+---------+
| 1 | Color |
| 2 | Type |
| 3 | Destiny |
+----+---------+
Attributes:
+----+--------------+--------------+-----------+
| Id | Value | DefinitionId | ProductId |
+----+--------------+--------------+-----------+
| 1 | Brown | 1 | 2 |
| 2 | Yellow | 1 | 1 |
| 3 | Sport | 3 | 1 |
| 4 | Jelly shoes | 2 | 1 |
| 5 | Normal shoes | 2 | 2 |
+----+--------------+--------------+-----------+
In AttributesDefinitions I have wanted attributes definitions.
In Attributes I have attributes and their values.
Each Product has many attributes, but only 1 of each type (attribute definition).
My task is to make a view containing list of products and all their attributes values.
It should look like this:
ProductsWithAttributesView:
+---------+--------+--------------+---------+
| Product | Color | Type | Destiny |
+---------+--------+--------------+---------+
| Shoe1 | Yellow | Jelly shoes | Sport |
| Shoe2 | Brown | Normal shoes | NULL |
| Shoe3 | NULL | NULL | NULL |
+---------+--------+--------------+---------+
The purpose of this is getting list of products on B2B platform and being able to filter them by values of attributes.
Any help how can I achieve that ?

Answer 1

I use code from CaitLAN Jenner to present my solution, but I`m not sure if you can make view which will dynamically adapt when new category is added.
CREATE TABLE Products
(
Id INT PRIMARY KEY,
Name VARCHAR(255)
);
INSERT INTO Products (Id,Name)
VALUES (1,'Car'),(2,'Motorcycle'),(3,'Bicycle')
CREATE TABLE AttributesDefinition
(
Id INT PRIMARY KEY,
Name VARCHAR(255)
);
INSERT INTO AttributesDefinition (Id,Name)
VALUES (1,'Number of wheels'),(2,'People'),(3,'Engine')
CREATE TABLE Attributes
(
Id INT,
Name VARCHAR(255),
Value VARCHAR(255),
DefinitionId INT FOREIGN KEY REFERENCES AttributesDefinition (Id),
ProductId INT FOREIGN KEY REFERENCES Products (Id)
);
INSERT INTO Attributes (Id, Name, Value, DefinitionId, ProductId)
VALUES (1,'Number of wheels','4',1,1),
(2,'Number of wheels','2',1,2),
(3,'Number of wheels','2',1,3),
(4,'People','4',2,1),
(5,'People','2',2,2),
(6,'People','1',2,3),
(7,'Engine','V6',3,1),
(8,'Engine','V2',3,2)
CREATE VIEW ProductsWithAttributesView AS
SELECT
products.Name as 'Products',
atr1.Value As 'Number of wheels',
atr2.Value As 'People',
atr3.Value As 'Engine'
FROM Products AS products
LEFT JOIN Attributes AS atr1 ON atr1.ProductId = products.Id AND atr1.DefinitionId = 1
LEFT JOIN Attributes AS atr2 ON atr2.ProductId = products.Id AND atr2.DefinitionId = 2
LEFT JOIN Attributes AS atr3 ON atr3.ProductId = products.Id AND atr3.DefinitionId = 3
Result
Products | Number of wheels | People | Engine
Car | 4 | 4 | V6
Motorcycle| 2 | 2 | V2
Bicycle | 2 | 1 | NULL
Edit. This one with pivot:
CREATE VIEW ProductsWithAttributesView2 AS
WITH pivot_data AS
(
SELECT products.Name as Products, -- Grouping Column
def.Name as AtrName, -- Spreading Column
Value -- Aggregate Column
FROM Attributes atr
INNER JOIN Products products ON atr.ProductId = products.Id
INNER JOIN AttributesDefinition def ON def.Id = atr.DefinitionId
)
SELECT Products, [Number of wheels],[People],[Engine]
FROM pivot_data
PIVOT (max(value) FOR AtrName IN ([Number of wheels],[People],[Engine])) AS p;

Answer 2

As I stated in my comment, I strongly disagree with the schema you've described because it appears to me that the Products table should have either a one-to-many or many-to-many relationship with Attributes. In other words, one Product can have many Attributes, and many Products can share the same Attribute. Additionally, because of the design you've mentioned and what your end goal is (a Product with an arbitrary-length list of attributes as columns) what your asking for may not be possible. You might could achieve those results with a carefully crafted PIVOT statement within the View definition. First let me know if the code below works.
With all of that said, if I make the assumption that you are using T-SQL, then this code will create the tables you've described and create a View based performing a JOIN on the tables. Hopefully this pushes you in the correct direction for moving forward.
CREATE TABLE Products
(
Id INT PRIMARY KEY,
Name VARCHAR(255)
);
CREATE TABLE AttributesDefinition
(
Id INT PRIMARY KEY,
Name VARCHAR(255)
);
CREATE TABLE Attributes
(
Id INT,
Name VARCHAR(255),
Value VARCHAR(255),
DefinitionId INT FOREIGN KEY REFERENCES AttributesDefinition (Id),
ProductId INT FOREIGN KEY REFERENCES Products (Id)
);
CREATE VIEW ProductsWithAttributesView AS
SELECT p.Name AS Products
,ad.Name AS AttributeDefinition
,a.Name AS AttributeName
,a.Value AS AttributeValue
FROM Products p
INNER JOIN Attributes a ON p.Id = a.ProductId
INNER JOIN AttributesDefinition ad ON ad.Id = a.DefinitionId;
SELECT * FROM ProductsWithAttributesView;