foreign key mssql

1A FOREIGN KEY is a key used to link two tables together.
2A FOREIGN KEY is a field (or collection of fields) in one table that refers to the PRIMARY KEY in another table.
3The table containing the foreign key is called the child table, and the table containing the candidate key is called the referenced or parent table.
4
5Example:
6# creating table users
7CREATE TABLE users(
8	user_id INT NOT NULL,
9  	user_name VARCHAR(64) NOT NULL,
10  	user_pass VARCHAR(32) NOT NULL,
11  	PRIMARY KEY(user_id);
12);
13# adding user data
14INSERT INTO users VALUES(1,"Raj","raj@123");
15
16# creating table orders
17CREATE TABLE orders(
18	order_id INT NOT NULL,
19  	order_description VARCHAR(255),
20  	orderer_id INT NOT NULL,
21  	PRIMARY KEY(order_id),
22  	FOREIGN KEY (orderer_id) REFERENCES users(user_id)
23);
24# adding order data
25INSERT INTO orders VALUES(1,"Daily groceries",1);

1CREATE TABLE Sales.TempSalesReason 
2   (
3      TempID int NOT NULL, Name nvarchar(50)
4      , CONSTRAINT PK_TempSales PRIMARY KEY NONCLUSTERED (TempID)
5      , CONSTRAINT FK_TempSales_SalesReason FOREIGN KEY (TempID)
6        REFERENCES Sales.SalesReason (SalesReasonID)
7        ON DELETE CASCADE
8        ON UPDATE CASCADE
9   )
10;
11

1/*Creating Foreign Key Constraint*/
2ALTER TABLE ForeignKeyTable ADD CONSTRAINT ForeignKeyTable_foreignKeyColumn_FK
3FOREIGN KEY (foreignKeyColumn) REFERENCES PrimaryKeyTable (PrimaryKeyColumn)