SQL

how to define a composite primary key in sql

CREATE TABLE person(id INT, 
					name TEXT,
					PRIMARY KEY (id, name)
				   );

composite primary key sql

CREATE TABLE student
(rollNumber INT, 
name VARCHAR(30), 
class VARCHAR(30), 
section VARCHAR(1), 
mobile VARCHAR(10),
PRIMARY KEY (rollNumber, mobile)); -- This thing

how to define a non primary composite key in sql

ALTER TABLE dbo.YourTable
ADD CONSTRAINT UC_YourTable_Col1_Col2
UNIQUE(Col1, Col2)

composite primary key sql

CREATE TABLE student
(rollNumber INT, 
name VARCHAR(30), 
class VARCHAR(30), 
section VARCHAR(1), 
mobile VARCHAR(10),
PRIMARY KEY (rollNumber, mobile));