<HTML ><HEAD ><TITLE >Database Connection Functions</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.64 "><LINK REV="MADE" HREF="mailto:pgsql-docs@postgresql.org"><LINK REL="HOME" TITLE="libpq++ - C++ Binding Library" HREF="index.html"><LINK REL="PREVIOUS" TITLE="libpq++ Classes" HREF="libpqpp-classes.html"><LINK REL="NEXT" TITLE="Query Execution Functions" HREF="libpqpp-exec.html"><LINK REL="STYLESHEET" TYPE="text/css" HREF="stylesheet.css"><META NAME="creation" CONTENT="2002-11-27T04:23:11"></HEAD ><BODY CLASS="SECT1" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#840084" ALINK="#0000FF" ><DIV CLASS="NAVHEADER" ><TABLE WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" ><SPAN CLASS="APPLICATION" >libpq++</SPAN > - C++ Binding Library</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="libpqpp-classes.html" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="libpqpp-exec.html" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="SECT1" ><H1 CLASS="SECT1" ><A NAME="libpqpp-connect" >1.4. Database Connection Functions</A ></H1 > <P > <P ></P ></P><UL ><LI > <P > <TT CLASS="FUNCTION" >PgConnection</TT > makes a new connection to a backend database server. </P><PRE CLASS="SYNOPSIS" >PgConnection::PgConnection(const char *conninfo)</PRE ><P> The <TT CLASS="PARAMETER" ><I >conninfo</I ></TT > string is the same as for the underlying <SPAN CLASS="APPLICATION" >libpq</SPAN > <TT CLASS="FUNCTION" >PQconnectdb</TT > function. </P > <P > Although typically called from one of the access classes, a connection to a backend server is possible by creating a <TT CLASS="CLASSNAME" >PgConnection</TT > object. </P > </LI ><LI > <P > <TT CLASS="FUNCTION" >ConnectionBad</TT > returns whether or not the connection to the backend server succeeded or failed. </P><PRE CLASS="SYNOPSIS" >bool PgConnection::ConnectionBad() const</PRE ><P> Returns true if the connection failed. </P > </LI ><LI > <P > <TT CLASS="FUNCTION" >Status</TT > returns the status of the connection to the backend server. </P><PRE CLASS="SYNOPSIS" >ConnStatusType PgConnection::Status()</PRE ><P> Returns either <TT CLASS="SYMBOL" >CONNECTION_OK</TT > or <TT CLASS="SYMBOL" >CONNECTION_BAD</TT > depending on the state of the connection. </P > </LI ><LI > <P > <TT CLASS="FUNCTION" >PgDatabase</TT > makes a new connection to a backend database server. </P><PRE CLASS="SYNOPSIS" >PgDatabase(const char *conninfo)</PRE ><P> After a <TT CLASS="CLASSNAME" >PgDatabase</TT > has been created it should be checked to make sure the connection to the database succeeded before sending queries to the object. This can easily be done by retrieving the current status of the <TT CLASS="CLASSNAME" >PgDatabase</TT > object with the <TT CLASS="FUNCTION" >Status</TT > or <TT CLASS="FUNCTION" >ConnectionBad</TT > methods. </P > </LI ><LI > <P > <TT CLASS="FUNCTION" >DBName</TT > returns the name of the current database. </P><PRE CLASS="SYNOPSIS" >const char *PgConnection::DBName()</PRE ><P> </P > </LI ><LI > <P > <TT CLASS="FUNCTION" >Notifies</TT > returns the next notification from a list of unhandled notification messages received from the backend. </P><PRE CLASS="SYNOPSIS" >PGnotify* PgConnection::Notifies()</PRE ><P> See <TT CLASS="FUNCTION" >PQnotifies</TT > in <SPAN CLASS="APPLICATION" >libpq</SPAN > for details. </P > </LI ></UL ><P> </P > </DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="libpqpp-classes.html" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="libpqpp-exec.html" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><SPAN CLASS="APPLICATION" >libpq++</SPAN > Classes</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" > </TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >Query Execution Functions</TD ></TR ></TABLE ></DIV ></BODY ></HTML >