|Chapter 4. The Query Language
You can create a new class by specifying the class name, along with all attribute names and their types:
CREATE TABLE weather ( city varchar(80), temp_lo int, -- low temperature temp_hi int, -- high temperature prcp real, -- precipitation date date );
Note that both keywords and identifiers are case-insensitive; identifiers can become case-sensitive by surrounding them with double-quotes as allowed by SQL92. Postgres SQL supports the usual SQL types int, float, real, smallint, char(N), varchar(N), date, time, and timestamp, as well as other types of general utility and a rich set of geometric types. As we will see later, Postgres can be customized with an arbitrary number of user-defined data types. Consequently, type names are not syntactical keywords, except where required to support special cases in the SQL92 standard. So far, the Postgres create command looks exactly like the command used to create a table in a traditional relational system. However, we will presently see that classes have properties that are extensions of the relational model.
|Populating a Class with Instances