| PostgreSQL | ||
|---|---|---|
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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 keywords are case-insensitive and identifiers are usually case-insensitive. Postgres allows SQL92 delimited identifiers (identifiers surrounded by double-quotes) to include mixed-case and spaces, tabs, etc.
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.
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