SQL Server and date + 1 result

Question

In case of the SQL Server. Say, if I have a table with [myDate] column that is of the type datetime, what would adding 1 to it mean in the following context?

SELECT * 
  FROM [myTable] 
 WHERE [myDate] + 1 > @someDate

Answer 1

It adds one day (exactly 24 hours)

However, your query is more correct this way. The function or processing on the column usually invalidates index usage if there is one of that column

WHERE [myDate] > @someDate - 1

OR

WHERE [myDate] > DATEADD(day, -1, @someDate)

Answer 2

Use the DATEADD function (see MSDN docs for DATEADD for details):

SELECT * 
  FROM dbo.myTable
 WHERE DATEADD(D, 1, myDate) > @someDate

DATEADD allows you to add any of the usual date parts (day, month, year) and also time parts (hours, minutes, seconds) etc.