What is the difference between datetime and smalldatetime in sql server

These types align with the SQL Standard. They are more portable. When you convert to date and time data types, SQL Server rejects all values it can't recognize as dates or times.

This section describes what occurs when a smalldatetime data type is converted to other date and time data types. For a conversion to date , the year, month, and day are copied. The following code shows the results of converting a smalldatetime value to a date value. When the conversion is to time n , the hours, minutes, and seconds are copied.

The fractional seconds are set to 0. The following code shows the results of converting a smalldatetime value to a time 4 value. In any case, Microsoft recommends using date , time , datetime2 , or datetimeoffset for new work. See smalldatetime vs datetime2 and datetime vs datetime2 to see how each of these types compare against datetime2. Here, I set a smalldatetime variable to the same value as the datetime variable.

This causes the value to be converted to smalldatetime and we can then use a SELECT statement to see the actual value that was assigned to each variable. The datetime variable rounds up the fractional seconds part.

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Tutorials, references, and examples are constantly reviewed to avoid errors, but we cannot warrant full correctness of all content. While using W3Schools, you agree to have read and accepted our terms of use , cookie and privacy policy. This will produce output with names of employees and year, month and days worked. We can include hours, minutes, seconds and even milliseconds but this usually is not necessary in this case.

Output will look like in image bellow: Note, all years and months are not the same. Some year has days, other days. February has 28 or 29 days, January has 31 days, April 30 days etc. Because of this, calculated result will probably have small deviation from real value. For example, 31 days means 1 month and 1 day if that month is April, but means 1 month and 0 days if month is January.

If total accuracy is not demanded, then you can consider this method since it is very simple. How to get precise time difference between two datetime or smalldatetime columns As you see, direct subtraction of dates can be useful in some scenarios but it is very limited.

First parameter specifies measurement unit. You can use these values:.