Difference between datetime and timestamp in SQL Server?
Essentially, DATETIME in SQL Server is a data type that records a moment in history with the format YYYY-MM-DD HH:MM:SS. It can record a time point from 1753-01-01 to as far as 9999-12-31, and it's accurate to 3.33ms.
Conversely, TIMESTAMP, also known as ROWVERSION, has nothing to do with time monitoring. It's an automated and unique binary identifier tailored for each row data in a table, updated whenever that row information changes. Its main usage is ensuring row uniqueness and handling concurrency control.
DATETIME playground:
ROWVERSION playground:
It is vital to note that TIMESTAMP/ROWVERSION's only responsibility is ensuring row consistency via an automatically-generated value, which is essential for optimistic concurrency control. The TIMESTAMP is a deprecated term, and it is recommended to use ROWVERSION nowadays for new designs.
The Inside Workingsof Datetime
The main purpose of a DATETIME field in SQL Server is to record an actual date and time event. Users manually set DATETIME either when inserting or updating records. This makes it ideal for instances where the time of happening is significant, such as recording the creation or updating of a record.
Timestamp or Rowversion: Your Data Unique Identifier!
The ROWVERSION, initially TIMESTAMP, works in a pretty cool and simple way. Whenever a row is inserted or updated, the ROWVERSION field is automatically updated with a unique binary number. SQL Server uses a database-wide counter to ensure each ROWVERSION value is completely unique.
Battling concurrency with Timestamp or Rowversion!
ROWVERSION is your secret weapon in a multi-user environment, where multiple transactions could potentially update the same record. With the ROWVERSION data type, SQL Server effectively manages concurrent changes to data by answering the question β "Has any other transaction modified this record since I last accessed it?" If the ROWVERSION differs from when it was last read, the change is detected and appropriately sync'd, ensuring data integrity and consistency.
Practically Selecting Datetime or Timestamp/Rowversion
Ideal situations for DATETIME:
- Documenting when a notable event occurs or is expected to take place
- Logging the time data entries are made or changes occur
- Any scenario requiring a track of dates and times for decision-making
Perfect scenarios for TIMESTAMP/ROWVERSION:
- Identifying if and when data rows change β an optimal method for data synchronization
- Implementing a mechanism to resolve conflicts when making data updates
- Tracking changes in a version history of data rows
Guidelines & Common Missteps with Datetime and Timestamp
Beware of performance
ROWVERSION may seem perfect for any SQL development, but beware! It can lead to an increase in write operations due to constant updates, which could cause a strain on your server's performance over time.
Best practices
Always store dates in UTC format when dealing with global applications. This ensures clarity by avoiding time zone variations.
Be cautious of
You cannot interpret ROWVERSION as an actual time value β it's a binary number. Don't confuse ROWVERSION with DATETIME. They serve different purposes!
Happy coding!π©βπ»
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