SQL Primary Keys Creating a Primary Key
Example
CREATE TABLE Employees (
Id int NOT NULL,
PRIMARY KEY (Id),
...
);
This will create the Employees table with 'Id' as its primary key. The primary key can be used to uniquely identify the rows of a table. Only one primary key is allowed per table.
A key can also be composed by one or more fields, so called composite key, with the following syntax:
CREATE TABLE EMPLOYEE (
e1_id INT,
e2_id INT,
PRIMARY KEY (e1_id, e2_id)
)
