```r
require(RPostgreSQL)
require(rpostgis)
require(sf)
require(mapview)
require(leaflet.extras)
library(tmap)
require(raster)
require(rgdal)

mapviewOptions(basemaps =c("Esri.WorldImagery","Esri.WorldShadedRelief", "Stamen.Terrain"))

conn <- dbConnect("PostgreSQL", host = "postgis",
  dbname = "gis_course" ,user = "gis_course", password = "gis_course123")
```