Truncate seconds and milliseconds in SQL

One way is to convert it to smalldatetime for the assignment (and back as needed). smalldatetime always has seconds and beyond set to 00.

SELECT CONVERT(smalldatetime, GETDATE())

As this may round up or down, another way to safely truncate the seconds would be this:

SELECT CONVERT(datetime, CONVERT(nchar(16), GETDATE(), 120), 120)

The conversion code 120 returns the format yyyy-mm-dd hh:mi:ss.

There are a number of ways to go about doing this.

For example, you could convert the generated datetime from GetDate() to a smalldatetime first, à la:

CAST(GetDate() AS smalldatetime)

To be clear, this will round the generated seconds up (or down) to the nearest minute depending up the value of the current second.

_EDIT:

Alternatively, you can have SQL Server truncate a datetime for you for a "cleaner" (READ: no rounding, since the value is pre-truncated) conversion to smalldatetime:

CAST(DateAdd(minute, DateDiff(minute, 0, GetDate()), 0) AS smalldatetime)

For truncation:

SELECT SMALLDATETIMEFROMPARTS(
         datepart(year  ,dt)
        ,datepart(month ,dt)
        ,datepart(day   ,dt)
        ,datepart(hour  ,dt)
        ,datepart(minute,dt)
      ) 
FROM (SELECT GETDATE()) t(dt)