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><A
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>2.3. Creating a New Table</A
></H1
><P
> You can create a new table by specifying the table
name, along with all column names and their types:
</P><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>
You can enter this into <TT
CLASS="COMMAND"
>psql</TT
> with the line
breaks. <TT
CLASS="COMMAND"
>psql</TT
> will recognize that the command
is not terminated until the semicolon.
</P
><P
> White space (i.e., spaces, tabs, and newlines) can be used freely
in SQL commands. That means you can type the command aligned
differently than above, or even all on one line. Two dashes
(<SPAN
CLASS="QUOTE"
>"<TT
CLASS="LITERAL"
>--</TT
>"</SPAN
>) introduce comments.
Whatever follows them is ignored up to the end of the line. SQL
is case insensitive about key words and identifiers, except
when identifiers are double-quoted to preserve the case (not done
above).
</P
><P
> <TT
CLASS="TYPE"
>varchar(80)</TT
> specifies a data type that can store
arbitrary character strings up to 80 characters in length.
<TT
CLASS="TYPE"
>int</TT
> is the normal integer type. <TT
CLASS="TYPE"
>real</TT
> is
a type for storing single precision floating-point numbers.
<TT
CLASS="TYPE"
>date</TT
> should be self-explanatory. (Yes, the column of
type <TT
CLASS="TYPE"
>date</TT
> is also named <TT
CLASS="STRUCTFIELD"
>date</TT
>.
This might be convenient or confusing — you choose.)
</P
><P
> <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> supports the standard
<ACRONYM
CLASS="ACRONYM"
>SQL</ACRONYM
> types <TT
CLASS="TYPE"
>int</TT
>,
<TT
CLASS="TYPE"
>smallint</TT
>, <TT
CLASS="TYPE"
>real</TT
>, <TT
CLASS="TYPE"
>double
precision</TT
>, <TT
CLASS="TYPE"
>char(<TT
CLASS="REPLACEABLE"
><I
>N</I
></TT
>)</TT
>,
<TT
CLASS="TYPE"
>varchar(<TT
CLASS="REPLACEABLE"
><I
>N</I
></TT
>)</TT
>, <TT
CLASS="TYPE"
>date</TT
>,
<TT
CLASS="TYPE"
>time</TT
>, <TT
CLASS="TYPE"
>timestamp</TT
>, and
<TT
CLASS="TYPE"
>interval</TT
>, as well as other types of general utility
and a rich set of geometric types.
<SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> can be customized with an
arbitrary number of user-defined data types. Consequently, type
names are not key words in the syntax, except where required to
support special cases in the <ACRONYM
CLASS="ACRONYM"
>SQL</ACRONYM
> standard.
</P
><P
> The second example will store cities and their associated
geographical location:
</P><PRE
CLASS="PROGRAMLISTING"
>CREATE TABLE cities (
name varchar(80),
location point
);</PRE
><P>
The <TT
CLASS="TYPE"
>point</TT
> type is an example of a
<SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
>-specific data type.
</P
><P
>
Finally, it should be mentioned that if you don't need a table any
longer or want to recreate it differently you can remove it using
the following command:
</P><PRE
CLASS="SYNOPSIS"
>DROP TABLE <TT
CLASS="REPLACEABLE"
><I
>tablename</I
></TT
>;</PRE
><P>
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