Primary Keys & Foreign Keys

PK rules:

• cannot be null

• unique to that table

• one primary key per a row

Note: foreign keys do need to reference a primary key

Primary Key

CREATE TABLE tableName (
	varName0 INT PRIMARY KEY,
  varName1 INT);

CREATE TABLE tableName (
	varName0 INT,
  varName1 INT,
	PRIMARY KEY (varName0, varName1));

Foreign Key

CREATE TABLE otherTable (
	varName0 INT,
	varName1 INT,
	FOREIGN KEY (varName1) REFERENCES tableName (varName1));