строку  

where timestamp_field between :X and :Y

заменить на

where cast(timestamp_field as date) between :X and :Y 

используем
where timestamp_field cstd between :X and :Y 

cstd ->  Ctrl+Left cast(Ctrl+Right as date) | = \pw cast(\nw as date) |

или с командами 'начало слова/конец слова'
cstd ->  BeginWord cast(EndWord as date) | = \bw cast(\ew as date) |