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();
});ALTER TABLE table_name
DROP CONSTRAINT fk_name;An index on a table is a data structure that makes random access to the rows
fast and efficient. It helps to optimize the internal organization of a table
as well.
A foreign key is simply a pointer to a corresponding column in another table
that forms a referential constraint between the two tables.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)
)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)
)ALTER TABLE your_table ADD FOREIGN KEY (your_column) REFERENCES other_table(other_column);