Answers for "create table with foreign key in sql"

SQL

mysql add foreign key

-- On Create
CREATE TABLE tableName (
    ID INT,
    SomeEntityID INT,
    PRIMARY KEY (ID),
    FOREIGN KEY (SomeEntityID)
        REFERENCES SomeEntityTable(ID)
        ON DELETE CASCADE
);

-- On Alter, if the column already exists but has no FK
ALTER TABLE
  tableName
ADD
  FOREIGN KEY (SomeEntityID) REFERENCES SomeEntityTable(ID) ON DELETE CASCADE;
  
 -- Add FK with a specific name
 -- On Alter, if the column already exists but has no FK
ALTER TABLE
  tableName
ADD CONSTRAINT fk_name
  FOREIGN KEY (SomeEntityID) REFERENCES SomeEntityTable(ID) ON DELETE CASCADE;

Posted by: Guest on April-27-2020

create table mysql with foreign key

CREATE TABLE Orders (
    OrderID int NOT NULL,
    OrderNumber int NOT NULL,
    PersonID int,
    PRIMARY KEY (OrderID),
    FOREIGN KEY (PersonID) REFERENCES Persons(PersonID)
);

Posted by: Guest on November-03-2020

Foreign Key in sql

CREATE TABLE Students ( 	 /* Create table with foreign key - Way 1 */
    ID INT NOT NULL
    Name VARCHAR(255)
    LibraryID INT
    PRIMARY KEY (ID)
    FOREIGN KEY (Library_ID) REFERENCES Library(LibraryID)
);

CREATE TABLE Students ( 	 /* Create table with foreign key - Way 2 */
    ID INT NOT NULL PRIMARY KEY
    Name VARCHAR(255)
    LibraryID INT FOREIGN KEY (Library_ID) REFERENCES Library(LibraryID)
);


ALTER TABLE Students 	 /* Add a new foreign key */
ADD FOREIGN KEY (LibraryID)
REFERENCES Library (LibraryID);

Posted by: Guest on July-06-2021

Source

What is foreign key?

Foreign Key is a non-key attribute which is derived from the primary key 
of another table which links those tables together.

Posted by: Guest on November-23-2020

Code answers related to "create table with foreign key in sql"

Code answers related to "SQL"

Browse Popular Code Answers by Language

Python

Javascript

Whatever

Shell/Bash

CSS

Html

PHP

SQL

Java

Answers for "create table with foreign key in sql"

Code answers related to "create table with foreign key in sql"

Code answers related to "SQL"

Browse Popular Code Answers by Language

Popular Programming Languages

Advertisements

Company

Compilers

Help

Connect with us