def sql_operator(operator, field)
      raise ScopedSearch::QueryNotSupported, "the operator '#{operator}' is not supported for field type '#{field.type}'" if !field.virtual? and [:like, :unlike].include?(operator) and !field.textual?
      SQL_OPERATORS[operator]
    end
def sql_operator(operator, field)
      raise ScopedSearch::QueryNotSupported, "the operator '#{operator}' is not supported for field type '#{field.type}'" if !field.virtual? and [:like, :unlike].include?(operator) and !field.textual?
      SQL_OPERATORS[operator]
    end
Return the SQL operator to use given an operator symbol and field definition.

 By default, it will simply look up the correct SQL operator in the SQL_OPERATORS
 hash, but this can be overridden by a database adapter.