Which is better in MySQL: datetime or timestamp?

[mikechen]

I’m developing a web application with PHP and MySQL, and I need to decide how to handle date and time data in my database. I’m unsure whether to use the datetime or the timestamp data type.

Although I’ve read that both types can store date and time, I’m not clear on their differences. Which one is more suitable for a typical web application? Are there particular pros and cons that I should consider?

Since I’m working with PHP for the server-side, I’d really appreciate insights on how each type interacts with it. Any guidance on when to choose one over the other would be extremely beneficial.

[Noah_Fire]

I’ve used both a ton, and datetime wins for most web apps. It’s predictable; you store exactly what you put in, without weird conversions happening behind the scenes. When you’re debugging or doing database work, you can see the actual values your app stored.

Timestamp can catch you off guard. I’ve had a production nightmare where a routine data fix updated records with current timestamps because I forgot about the auto-update behavior. Datetime gives you full control over when values change.

Both types integrate well with PHP’s DateTime objects, but datetime is far more flexible for historical data or scheduling in the future. As for storage, that only matters if you have millions of records, and even then, datetime’s reliability outweighs saving a few bytes.

[JumpingRabbit]

I’ve used both across different projects, and it really depends on what you need rather than one being better overall. Something nobody mentioned yet - null values and defaults behave differently. Datetime handles nulls fine, but timestamp has weird quirks with NOT NULL constraints that’ll randomly insert current timestamps when you don’t expect it.

Migration’s another thing to watch. I moved an app between servers with different timezone settings once, and all the timestamp data shifted while datetime stayed put. Now I always think about where the app’s gonna run before picking one.

For PHP, both work fine with PDO and mysqli. But datetime’s easier to debug since what you see in phpMyAdmin is exactly what got stored. Performance-wise, they’re basically the same unless you’re dealing with huge datasets where saving 4 bytes per record actually matters.

[sofiap]

In my experience with PHP and MySQL, I strongly prefer using datetime over timestamp. The primary advantage is that datetime preserves the exact date and time without making any automatic timezone conversions, which can lead to confusion especially when users are in different timezones. In contrast, timestamp records times in UTC, which can complicate things when you need to handle time zones manually.

Moreover, the timestamp column auto-updates its value to the current time when you modify a row, creating potential issues during data migrations or updates. This auto-update feature can be beneficial in some scenarios, but it introduces unpredictability. For these reasons, datetime tends to be the safer choice for most web applications.

[lily_luminesce]

The Problem: You’re developing a PHP web application using MySQL and need to choose between DATETIME and TIMESTAMP data types for storing date and time information in your database. You’re unsure which is more suitable for a typical web application and how each interacts with PHP.

Understanding the “Why” (The Root Cause):

The core issue isn’t about choosing between DATETIME and TIMESTAMP directly; it’s about effectively managing date and time operations across your entire application. Both data types have their strengths and weaknesses, but the real challenge lies in handling conversions, time zones, and data synchronization. Relying solely on the database type to solve timezone issues or data consistency is insufficient.

The solution proposed is to automate date processing workflows instead of focusing on minor differences between DATETIME and TIMESTAMP. This approach acknowledges that regardless of your choice, you’ll still need to manage many date-related operations in your PHP application.

Step-by-Step Guide:

Step 1: Automate Your Date Handling Processes. Instead of manually handling date conversions, timezone adjustments, and data synchronization within your PHP code, build an automated workflow. This workflow will handle the complexities irrespective of the database column type chosen. This might involve:

• Creating functions or classes in your PHP application to handle date conversions and timezone handling using the DateTime class. These should account for different input formats, user locations, and the target format for your database.
• Building scripts or using task runners (e.g., cron jobs) to perform regular data synchronization and updates, ensuring consistency across your application and database. This can include tasks like bulk-updating records when timezone rules change.
• Consider using a dedicated library to handle timezone management and conversions.

Step 2: Consider Using a Consistent Time Zone. For simplicity, consider storing all dates and times in a single, consistent timezone (e.g., UTC) within your database, regardless of whether you choose DATETIME or TIMESTAMP. Then, use your automated workflow to convert these dates to the appropriate timezone for display to the user based on their location.

Step 3: Choose Your Database Type (Secondary Consideration). After automating your data handling, the choice between DATETIME and TIMESTAMP becomes less critical. However:

• DATETIME: Offers greater precision and explicit control. You store the exact value you entered. This improves debugging and is generally preferred for better readability and predictable behaviour.

• TIMESTAMP: Offers automatic updates upon row modification and automatic conversion to UTC. This can simplify certain tasks but introduces the risk of unintentional updates and requires careful timezone management in your application.

Common Pitfalls & What to Check Next:

• Timezone Handling: The most common pitfall is inconsistent or incorrect timezone handling. Double-check all date and time functions in your application to ensure they account for time zones appropriately.

• Data Validation: Always validate user-supplied date and time data to prevent unexpected inputs that may lead to errors or inconsistencies.

• Database Migrations: When migrating your application, ensure that your date-handling procedures are migrated correctly to prevent data loss or corruption.

Still running into issues? Share your (sanitized) config files, the exact command you ran, and any other relevant details. The community is here to help!

[Isaac_Cosmos]

In my experience, the decision between datetime and timestamp largely depends on the specific needs of your application. While timestamp has the limitation of only supporting dates from 1970 to 2038, making it unsuitable for many use cases like birthdates, datetime offers a much broader range from 1000 to 9999. However, timestamp is more storage efficient, requiring only 4 bytes compared to 8 bytes for datetime, which can be crucial with large datasets. Additionally, timestamp’s automatic timezone conversion to UTC is advantageous for applications with a global user base. Both types integrate well with PHP’s DateTime objects, so factor these considerations carefully when making your choice.

[avamtz]

i’ve used timestamp for years - zero problems. the 2038 limit doesn’t matter for most apps since ur storing recent data anyway. plus the automatic UTC conversion is a lifesaver when you have users in different timezones.