lib/dataset/query.js
function (cols) {
            var ret;
            if (!this.hasSelectSource) {
                ret = this.select.apply(this, arguments);
            } else {
                ret = this.mergeOptions();
            }
            return ret;
        }
function (cols) {
            var ret;
            if (!this.hasSelectSource) {
                ret = this.select.apply(this, arguments);
            } else {
                ret = this.mergeOptions();
            }
            return ret;
        }
function ( cols ) { var ret ; if ( ! this . hasSelectSource ) { ret = this . select . apply ( this , arguments ) ; } else { ret = this . mergeOptions ( ) ; } return ret ; }
Selects the columns if only if there is not already select sources.

@example

var ds = DB.from("items"); //SELECT * FROM items

ds.select("a"); //SELECT a FROM items;
ds.select("a").selectIfNoSource("a", "b"). //SELECT a FROM items;
ds.selectIfNoSource("a", "b"). //SELECT a, b FROM items;

@param cols columns to select if there is not already select sources.
@return {patio.Dataset} a cloned dataset with the appropriate select sources.
Selects the columns if only if there is not already select sources .