Difference between DateTime and DateTime2 in SQL Server
DateTime2 is the new Data Type introduced in Sql Server 2008 for storing Date and Time value. As per MSDN, Microsoft Suggests to use this new Data Type for new work instead of DateTime.
Following table summarizes some of the major difference between this new DateTime2 and the old DateTime Data Type.
DateTime | DateTime2[(n)] | |
Min Value | 1753-01-01 00:00:00 | 0001-01-01 00:00:00 |
Max Value | 9999-12-31 23:59:59.997 | 9999-12-31 23:59:59.9999999 |
Storage Size | 8 Bytes | 6 to 8 bytes Note: Parameter n is optional and if it is not specified then fractional seconds precision is 7 digit and it can be from 0 to 7 digit. For fractional seconds precision <3, takes 6 bytes For fractional seconds precision 3 or 4 it will take 7 bytes For fractional seconds precision >4 it will take 8 bytes |
Usage | Declare @now datetime | Declare @now datetime2(7) |
Compliance | Is not an ANSI/ISO compliant | Is an ANSI/ISO compliant |
Current Date and Time function | GetDate() – It returns DB Current Date and Time of DateTime Data Type Example: SELECT GETDATE() | SYSDATETIME()– It returns DB Current Date and Time of DateTime2 Data Type Example:SELECT SYSDATETIME() |
+/- days | WORKS Example: | FAILS – Need to use only DateAdd function Example: |
DateTime2 with fractional seconds precision of 3 is same as DateTime data type. And DateTime2(3) uses 7 bytes of storage instead of 8 byte which old DateTime datatype uses and it also provides higher date range (i.e. 0001-01-01 to 9999-12-31 ) compared to DateTime data type. Now let us see this with an example:
DECLARE @nowDateTime DATETIME = GETDATE(), @nowDateTime2 DATETIME2(3)= SYSDATETIME() SELECT DATALENGTH(@nowDateTime) 'DateTime Storage Size' , DATALENGTH(@nowDateTime2) 'DateTime2(3) Storage Size' |
Result: DateTime Storage Size DateTime2 Storage Size --------------------- ---------------------- 8 7
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