\name{variableColumns}
\alias{variableColumns}
\alias{variableDomain}
\alias{variableType}
\title{Extracts metadata about variables a StatShop database.  
}
\usage{ 
variableColumns(variableData, vars)
variableDomain(variableData, vars)
variableType(variableData, vars)
}
\arguments{
  \item{variableData}{Variable metadata structure, output of
    \code{getVariableData}}
  \item{vars}{Names of variables}
}
\value{
  Returns a vector (or list for \code{variableDomain}) containing (one
  for each variable) of the requested metadata.
}
\description{
  Reads information from the output of \code{getVariableMetadata} and
  extracts relevant bits.  These functions are written in two parts to
  minimize database reads.

  The function \code{variableColumns} returns the column names
  associated with the variables in the database.

  The function \code{variableType} returns \code{"ordered"}, \code{
    "factor"} or \code{"numeric"} depending on the type of the
  variable.  Note:  Due to a bug in StatShop, currently the ordered
  status is not properly saved, so all discrete variables are assumed to
  be ordered.

  The function returns a vector of possible states for the variable for
  each variable.
}
\seealso{
  \code{\link{getVariableMetadata}}, \code{\link{getVariable}}
}
\examples{
### This example will only run if you have the StatShop test databases
### installed on your machine.
StatShop <- Sys.getenv("STATSHOP")
if (StatShop == "") {
  warn("StatShop not installed, skipping test.")
} else {
  asp.dbConnect("mcmc_statistics_test","junit")
  ## Get metadata for the student model variables
  vd <- getVariableMetadata("system")
  vars <- listVariables("system")
  ## Extract bits of metadata.
  variableType(vd,vars)
  variableDomain(vd,vars)
  asp.dbDisconnect()
}
}
\keyword{database}