Sophie: postgresql8.4-docs-8.4.12-0.1mdv2010.2 i586

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>Chapter 32. <SPAN
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>ECPG</SPAN
> - Embedded <ACRONYM
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>SQL</ACRONYM
> in C</TD
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><A
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>32.2. Connecting to the Database Server</A
></H1
><P
>   One connects to a database using the following statement:
</P><PRE
CLASS="PROGRAMLISTING"
>EXEC SQL CONNECT TO <TT
CLASS="REPLACEABLE"
><I
>target</I
></TT
> [<SPAN
CLASS="OPTIONAL"
>AS <TT
CLASS="REPLACEABLE"
><I
>connection-name</I
></TT
></SPAN
>] [<SPAN
CLASS="OPTIONAL"
>USER <TT
CLASS="REPLACEABLE"
><I
>user-name</I
></TT
></SPAN
>];</PRE
><P>
   The <TT
CLASS="REPLACEABLE"
><I
>target</I
></TT
> can be specified in the
   following ways:

   <P
></P
></P><UL
><LI
><P
>      <TT
CLASS="LITERAL"
><TT
CLASS="REPLACEABLE"
><I
>dbname</I
></TT
>[<SPAN
CLASS="OPTIONAL"
>@<TT
CLASS="REPLACEABLE"
><I
>hostname</I
></TT
></SPAN
>][<SPAN
CLASS="OPTIONAL"
>:<TT
CLASS="REPLACEABLE"
><I
>port</I
></TT
></SPAN
>]</TT
>
     </P
></LI
><LI
><P
>      <TT
CLASS="LITERAL"
>tcp:postgresql://<TT
CLASS="REPLACEABLE"
><I
>hostname</I
></TT
>[<SPAN
CLASS="OPTIONAL"
>:<TT
CLASS="REPLACEABLE"
><I
>port</I
></TT
></SPAN
>][<SPAN
CLASS="OPTIONAL"
>/<TT
CLASS="REPLACEABLE"
><I
>dbname</I
></TT
></SPAN
>][<SPAN
CLASS="OPTIONAL"
>?<TT
CLASS="REPLACEABLE"
><I
>options</I
></TT
></SPAN
>]</TT
>
     </P
></LI
><LI
><P
>      <TT
CLASS="LITERAL"
>unix:postgresql://<TT
CLASS="REPLACEABLE"
><I
>hostname</I
></TT
>[<SPAN
CLASS="OPTIONAL"
>:<TT
CLASS="REPLACEABLE"
><I
>port</I
></TT
></SPAN
>][<SPAN
CLASS="OPTIONAL"
>/<TT
CLASS="REPLACEABLE"
><I
>dbname</I
></TT
></SPAN
>][<SPAN
CLASS="OPTIONAL"
>?<TT
CLASS="REPLACEABLE"
><I
>options</I
></TT
></SPAN
>]</TT
>
     </P
></LI
><LI
><P
>      an SQL string literal containing one of the above forms
     </P
></LI
><LI
><P
>      a reference to a character variable containing one of the above forms (see examples)
     </P
></LI
><LI
><P
>      <TT
CLASS="LITERAL"
>DEFAULT</TT
>
     </P
></LI
></UL
><P>

   If you specify the connection target literally (that is, not
   through a variable reference) and you don't quote the value, then
   the case-insensitivity rules of normal SQL are applied.  In that
   case you can also double-quote the individual parameters separately
   as needed.  In practice, it is probably less error-prone to use a
   (single-quoted) string literal or a variable reference.  The
   connection target <TT
CLASS="LITERAL"
>DEFAULT</TT
> initiates a connection
   to the default database under the default user name.  No separate
   user name or connection name can be specified in that case.
  </P
><P
>   There are also different ways to specify the user name:

   <P
></P
></P><UL
><LI
><P
>      <TT
CLASS="LITERAL"
><TT
CLASS="REPLACEABLE"
><I
>username</I
></TT
></TT
>
     </P
></LI
><LI
><P
>      <TT
CLASS="LITERAL"
><TT
CLASS="REPLACEABLE"
><I
>username</I
></TT
>/<TT
CLASS="REPLACEABLE"
><I
>password</I
></TT
></TT
>
     </P
></LI
><LI
><P
>      <TT
CLASS="LITERAL"
><TT
CLASS="REPLACEABLE"
><I
>username</I
></TT
> IDENTIFIED BY <TT
CLASS="REPLACEABLE"
><I
>password</I
></TT
></TT
>
     </P
></LI
><LI
><P
>      <TT
CLASS="LITERAL"
><TT
CLASS="REPLACEABLE"
><I
>username</I
></TT
> USING <TT
CLASS="REPLACEABLE"
><I
>password</I
></TT
></TT
>
     </P
></LI
></UL
><P>

   As above, the parameters <TT
CLASS="REPLACEABLE"
><I
>username</I
></TT
> and
   <TT
CLASS="REPLACEABLE"
><I
>password</I
></TT
> can be an SQL identifier, an
   SQL string literal, or a reference to a character variable.
  </P
><P
>   The <TT
CLASS="REPLACEABLE"
><I
>connection-name</I
></TT
> is used to handle
   multiple connections in one program.  It can be omitted if a
   program uses only one connection.  The most recently opened
   connection becomes the current connection, which is used by default
   when an SQL statement is to be executed (see later in this
   chapter).
  </P
><P
>   Here are some examples of <TT
CLASS="COMMAND"
>CONNECT</TT
> statements:
</P><PRE
CLASS="PROGRAMLISTING"
>EXEC SQL CONNECT TO mydb@sql.mydomain.com;

EXEC SQL CONNECT TO unix:postgresql://sql.mydomain.com/mydb AS myconnection USER john;

EXEC SQL BEGIN DECLARE SECTION;
const char *target = "mydb@sql.mydomain.com";
const char *user = "john";
EXEC SQL END DECLARE SECTION;
 ...
EXEC SQL CONNECT TO :target USER :user;</PRE
><P>
   The last form makes use of the variant referred to above as
   character variable reference.  You will see in later sections how C
   variables can be used in SQL statements when you prefix them with a
   colon.
  </P
><P
>   Be advised that the format of the connection target is not
   specified in the SQL standard.  So if you want to develop portable
   applications, you might want to use something based on the last
   example above to encapsulate the connection target string
   somewhere.
  </P
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