The CREATE TABLE command is used to specify a new relation by giving it
a name and specify its attributes and constraints. The attributes are 
specified first, and each attribute given a name, a data type to 
specify its domain of values, and any attribute constraints such as 
NOT NULL. The key, entity integrity, and referential integrity 
constraints can be specified within the C REATE TABLE statement, 
after the attributes are declared, or they can be added later using 
the ALTER TABLE command.