R/gta_sql_get_value.R

In global-trade-alert/gtasql:

# Roxygen documentation

#' Get a value from the SQL database. 
#'
#' Just a wrapper, really. Returns a scalar or a data frame, depending on how many results you have.
#' 
#' @param query Your query in SQL language (incl SQL naming!).
#' @param db.connection Specify the database connection you want to use. Default is 'pool'.
#'
#' @references www.globaltradealert.org
#' @author Global Trade Alert

gta_sql_get_value <- function(query=NULL,
                              db.connection="pool") {
  
    eval(parse(text=paste0("conn.get.value=poolCheckout(",db.connection,")")))
    
    
    sought.value=dbGetQuery(conn.get.value, query)
    poolReturn(conn.get.value)
    rm(conn.get.value)
    
    if(nrow(sought.value)==0){
      
      if(ncol(sought.value)==1){
        my.value=NA
      } else {
        names(sought.value)=gsub("_","\\.",names(sought.value))
        my.value=sought.value
      }
      
      
    } else {
      
      if(nrow(sought.value)==1 & ncol(sought.value)==1){
        my.value=sought.value[1,1]
      } else if (ncol(sought.value)==1){
        my.value=as.vector(sought.value[,1])
      } else {
        names(sought.value)=gsub("_","\\.",names(sought.value))
        my.value=sought.value
      }
    }

  return(my.value)
}