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>Creating a New Class</A
></H1
><P
> You can create a new class by specifying the class
name, along with all attribute names and their types:
<PRE
CLASS="PROGRAMLISTING"
>CREATE TABLE weather (
city varchar(80),
temp_lo int, -- low temperature
temp_hi int, -- high temperature
prcp real, -- precipitation
date date
);</PRE
> </P
><P
> Note that keywords are case-insensitive and identifiers
are usually case-insensitive.
<SPAN
CLASS="ACRONYM"
>Postgres</SPAN
> allows <SPAN
CLASS="ACRONYM"
>SQL92</SPAN
> <I
CLASS="FIRSTTERM"
>delimited identifiers</I
>
(identifiers surrounded by double-quotes) to include mixed-case and spaces, tabs, etc. </P
><P
> <SPAN
CLASS="PRODUCTNAME"
>Postgres</SPAN
> <SPAN
CLASS="ACRONYM"
>SQL</SPAN
> supports the usual
<SPAN
CLASS="ACRONYM"
>SQL</SPAN
> types <SPAN
CLASS="TYPE"
>int</SPAN
>,
<SPAN
CLASS="TYPE"
>float</SPAN
>, <SPAN
CLASS="TYPE"
>real</SPAN
>, <SPAN
CLASS="TYPE"
>smallint</SPAN
>, <SPAN
CLASS="TYPE"
>char(N)</SPAN
>,
<SPAN
CLASS="TYPE"
>varchar(N)</SPAN
>, <SPAN
CLASS="TYPE"
>date</SPAN
>, <SPAN
CLASS="TYPE"
>time</SPAN
>,
and <SPAN
CLASS="TYPE"
>timestamp</SPAN
>, as well as other types of general utility and
a rich set of geometric types. As we will
see later, <SPAN
CLASS="PRODUCTNAME"
>Postgres</SPAN
> 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 <SPAN
CLASS="ACRONYM"
>SQL92</SPAN
> standard.
So far, the <SPAN
CLASS="PRODUCTNAME"
>Postgres</SPAN
> 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.</P
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