sql - WHy doesn't my stored procedure work for same dates? -

why doesn't stored procedure work when pass same dates (i.e. , dates same) although have records these dates doesn't. why ?

 select      audits.pk_audits_auditid,       audits.fk_webusers_audits_userid,       web_users.name username,       districts.pk_districts_districtid,      districts.districtname,       orgs.pk_orgs_orgid, orgs.orgname,       audits.auditsuseractivity,       audits.auditsuseripaddress,      audits.auditsusersystemmacaddress,       convert(varchar, audits.auditsystementrydatetime, 113) auditsystementrydatetime      audits inner join     web_users on web_users.userid= audits.fk_webusers_audits_userid inner join     orgs on orgs.pk_orgs_orgid= web_users.fk_orgs_orgid_webusers inner join     districts on districts.pk_districts_districtid= orgs.fk_districts_orgs_districtid     convert(varchar, dateadd(day, -1, audits.auditsystementrydatetime)) >= @fromdate     , convert(varchar, audits.auditsystementrydatetime) <= @todate 

it doesn't work because auditsystementrydatetime presumably has time. suspect want logic as:

 convert(date, dateadd(day, -1, audits.auditsystementrydatetime)) >= @fromdate ,        convert(date, audits.auditsystementrydatetime) <= @todate 

in general, don't want convert datetime characters purpose other output.

but, better way write logic is:

where audits.auditsystementrydatetime >= dateadd(day, 1, @fromdate) ,       audits.auditsystementrydatetime < dateadd(day, 1, @todate) 

by keeping functions on constants, sql server can use index where clause. hmmm, adding of 1 day explain why no results. perhaps want:

where audits.auditsystementrydatetime >= @fromdate ,       audits.auditsystementrydatetime < dateadd(day, 1, @todate) 

this makes sense.