I am using QGIS Essen version (2.14.1). I am trying to filter my data based on dates. i ma wondering if a "between" operator exists like in SQL? I'm trying the following query but the results coming out are wrong. Or is it the date format which is a problem?

( (("all_ws_d_2" <= '01-09-16') and ("all_ws_d_3" >= '30-09-16')) or (("all_ws_d_2" >= '01-09-16') and ("all_ws_d_3" <= '30-09-16')) or (("all_ws_d_2" <= '01-09-16') and (("all_ws_d_3" => '01-09-16') and ("all_ws_d_3" <= '30-09-16' ))) or (("all_ws_d_2" >= '01-09-16') and (("all_ws_d_2" <= '30-09-16') and ("all_ws_d_3" >= '30-09-16'))) )