laravel foreign key
Schema::table('posts', function (Blueprint $table) {
$table->unsignedBigInteger('user_id');
$table->foreign('user_id')->references('id')->on('users');
});
OR
Schema::table('posts', function (Blueprint $table) {
$table->foreignId('user_id')->constrained();
});drop foreign key
ALTER TABLE table_name
DROP CONSTRAINT fk_name;foreign key
CREATE TABLE Employee(
EmployeeID int NOT NULL,
LastName varchar(50) NOT NULL,
FirstName varchar(20) NOT NULL,
Age int,
DeptNo int,
PRIMARY KEY (EmployeeID),
FOREIGN KEY (DeptNo) REFERENCES Department(DeptNo)
);foreign key
Foreign Key:
It is a column that comes from a different table and
using Foreign key tables are related each other
It is the primary key of another table
It can be duplicate or null for another table
Primary Key :
It is unique column in every table in a database
It can ONLY accept;
- nonduplicate values
- cannot be NULL
Unique Key:
Only unique value and also can contain NULLforeign key
USE Organization
CREATE TABLE Employee
(
Id INT PRIMARY KEY IDENTITY(1,1),
Name VARCHAR (50) NOT NULL,
Age INT,
Gender VARCHAR (50),
Dep_Id int FOREIGN KEY REFERENCES Department(Id),
Insur_Id int FOREIGN KEY REFERENCES Insurance(Id)
)foreign key
USE Organization
CREATE TABLE Employee_Office
(
Id INT PRIMARY KEY IDENTITY(1,1),
Emp_Id int FOREIGN KEY REFERENCES Employee(Id),
Office_Id int FOREIGN KEY REFERENCES Office(Id)
)Copyright © 2021 Codeinu
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