Convert SQL server datetime fields to compare date parts only, with indexed lookups

Question

I\'ve been doing a convert(varchar,datefield,112) on each date field that I\'m using in \'between\' queries in SQL server to ensure that I\'m only accounting fo

Answer 1

Converting numeric types to string values (a type of Boxing) is not the best performing method of doing what you are looking for. Its not really about index-able, because the actual column type is date time.

If you are looking for the best way query for dates, then your example is right, but you may want to take into account the 3 ms precision difference in MSSQL. It can mean that records from one day can show up in another day's result.

This

select * from appointments where appointmentDate>='08-01-2008' and appointmentDate<'08-15-2008'

Should be this

select * from appointments where appointmentDate>='08-01-2008' and appointmentDate<='08-14-2008 23:59:59.996'