Scala: Guide for Data Science Professionals

Wrapping result sets in a stream

The JDBC ResultSet object plays very badly with Scala collections. The only real way of doing anything useful with it is to loop through it directly with a while loop. For instance, to get a list of the names of physicists in our database, we could write the following code:

// WARNING: poor Scala code
import Implicits._ // import implicit conversions

SqlUtils.usingConnection("test") { connection =>
  connection.withQuery("SELECT * FROM physicists") { resultSet =>
    var names = List.empty[String]
    while(resultSet.next) {
      val name = resultSet.getString("name")
      names = name :: names
    }
    names
  }
}
//=> List[String] = List(Paul Dirac, Albert Einstein, Marie Curie, Richard Feynman, Isaac Newton)

The ResultSet interface feels ...