

    \filetitle{dbextend}{Combine tseries observations from two or more databases}{dbase/dbextend}

	\paragraph{Syntax}

\begin{verbatim}
D = dbextend(D,D1,D2,...)
\end{verbatim}

\paragraph{Input arguments}

\begin{itemize}
\item
  \texttt{D} {[} struct {]} - Primary input database.
\item
  \texttt{D1}, \texttt{D2}, \ldots{} {[} struct {]} - Databases whose
  tseries observations will be used to extend or overwrite observations
  in the tseries objects of the same name in the primary database.
\end{itemize}

\paragraph{Output arguments}

\begin{itemize}
\itemsep1pt\parskip0pt\parsep0pt
\item
  \texttt{D} {[} struct {]} - Output database.
\end{itemize}

\paragraph{Description}

If more than two databases are combined then they are processed
one-by-one: the first is combined with the second, then the result is
combined with the third, and so on, using the following rules:

\begin{itemize}
\itemsep1pt\parskip0pt\parsep0pt
\item
  If two non-empty tseries objects with the same frequency are combined,
  the observations are spliced together. If some of the observations
  overlap the observations from the second tseries are used.
\item
  If two empty tseries objects are combined the first is used.
\item
  If a non-empty tseries is combined with an empty tseries, the
  non-empty one is used.
\item
  If two objects are combined of which at least one is a non-tseries
  object, the second input object is used.
\end{itemize}

\paragraph{Example}


