sql server datetime vs datetime2 with code examples

SQL Server provides two data types for storing date and time information: DATETIME and DATETIME2. Although both of these data types are used to store date and time information, there are several differences between them that can have a significant impact on the accuracy and performance of your data. In this article, we will compare and contrast the SQL Server DATETIME and DATETIME2 data types, exploring their differences, use cases, and code examples.

DATETIME

The DATETIME data type in SQL Server was introduced in SQL Server 7.0 and provides the ability to store date and time information in a single field. The data type is stored in 8 bytes, with 4 bytes used to store the date and 4 bytes used to store the time. The range of the DATETIME data type is January 1, 1753 to December 31, 9999. The default format for the DATETIME data type is "YYYY-MM-DD HH:MI:SS".

One of the biggest limitations of the DATETIME data type is that it only has a precision of 3 milliseconds. This means that if you need to store more precise information, such as the exact time an event occurred, the DATETIME data type may not be suitable. Additionally, the DATETIME data type is not time zone aware, which can be a problem if you need to store and compare data across multiple time zones.

DATETIME2

The DATETIME2 data type was introduced in SQL Server 2008 and provides a more advanced solution for storing date and time information. Unlike the DATETIME data type, the DATETIME2 data type has a much higher precision, ranging from 0 to 7 digits of precision. The range of the DATETIME2 data type is 0001-01-01 00:00:00.0000000 to 9999-12-31 23:59:59.9999999. The default format for the DATETIME2 data type is "YYYY-MM-DD HH:MI:SS.nnnnnnn", where nnnnnnn represents the fractional second.

In addition to its higher precision, the DATETIME2 data type is also time zone aware. This means that you can store and compare date and time information in different time zones, which can be useful when working with data from multiple locations. The DATETIME2 data type requires 6 to 8 bytes, depending on the precision specified.

Comparing DATETIME and DATETIME2

In terms of accuracy and performance, the DATETIME2 data type is the clear winner over the DATETIME data type. The higher precision of the DATETIME2 data type makes it a better choice for storing more accurate date and time information, while its time zone awareness makes it a better choice for working with data from multiple locations.

However, it's important to note that the DATETIME2 data type requires more space than the DATETIME data type, which can have an impact on the performance of your database. Additionally, the DATETIME2 data type is a newer data type and may not be supported by older systems or applications, so it may not always be the best choice for backwards compatibility.

Code Examples

Here are some code examples to illustrate the differences between the DATETIME and DATETIME2 data types in SQL Server:

Creating a DATETIME column:

CREATE TABLE Events (
    EventID INT PRIMARY KEY,
    EventName VARCHAR(50
),
    EventDateTime DATETIME
);

Creating a DATETIME2 column:

CREATE TABLE Events (
    EventID INT PRIMARY KEY,
    EventName VARCHAR(50),
    EventDateTime2 DATETIME2(7)
);

Inserting data into a DATETIME column:

INSERT INTO Events (EventID, EventName, EventDateTime)
VALUES (1, 'Event 1', '2022-01-01 10:00:00');

Inserting data into a DATETIME2 column:

INSERT INTO Events (EventID, EventName, EventDateTime2)
VALUES (1, 'Event 1', '2022-01-01 10:00:00.0000000');

Updating a DATETIME column:

UPDATE Events
SET EventDateTime = '2022-01-01 11:00:00'
WHERE EventID = 1;

Updating a DATETIME2 column:

UPDATE Events
SET EventDateTime2 = '2022-01-01 11:00:00.0000000'
WHERE EventID = 1;

Retrieving data from a DATETIME column:

SELECT EventID, EventName, EventDateTime
FROM Events
WHERE EventID = 1;

Retrieving data from a DATETIME2 column:

SELECT EventID, EventName, EventDateTime2
FROM Events
WHERE EventID = 1;

Conclusion

In conclusion, the SQL Server DATETIME and DATETIME2 data types both provide a way to store date and time information in a database. However, there are several differences between the two data types that can impact the accuracy and performance of your data. The DATETIME2 data type offers higher precision and time zone awareness, but requires more space and may not be supported by older systems or applications. Ultimately, the best choice between the two data types will depend on the specific needs of your database and the type of data you need to store.

Popular questions

1. What is the difference between SQL Server DATETIME and DATETIME2 data types?

The main difference between the SQL Server DATETIME and DATETIME2 data types is the level of precision they provide. The DATETIME data type provides a precision of 3.33 milliseconds, while the DATETIME2 data type provides a precision of 100 nanoseconds. The DATETIME2 data type also supports time zones, while the DATETIME data type does not.

2. What is the range of values that the SQL Server DATETIME data type can store?

The SQL Server DATETIME data type can store dates and times between January 1, 1753 and December 31, 9999.

3. What is the range of values that the SQL Server DATETIME2 data type can store?

The SQL Server DATETIME2 data type can store dates and times between January 1, 0001 and December 31, 9999.

4. What is the storage size of the SQL Server DATETIME data type?

The SQL Server DATETIME data type requires 8 bytes of storage space.

5. What is the storage size of the SQL Server DATETIME2 data type?

The SQL Server DATETIME2 data type requires 6 to 8 bytes of storage space, depending on the specified precision. The higher the precision, the more storage space required. For example, a DATETIME2(7) column would require 8 bytes, while a DATETIME2(0) column would require 6 bytes.

Tag

Databases.