code: function buildSelect () {
      // list of columns to select
      var columns = this.isSelectOnlyIds ? ['id'] : this.model.columnNames
      // add columns to select list
      _.each(columns, columnName => {
          // validate column name - throw error
          columnName = this.model.columnName(columnName, true)
          // get column spec
          var spec = this.model.columns[columnName]
          // add select column sql
          this.select.push(
              this.selectColumnSql(this.model, columnName, spec, this.table)
          )
      })
  }
docs: @function buildSelect
  
  build list of columns from the primary table to select
  
  @throws {Error}