Understanding MySQL timestamps: functions, features and application scenarios

MySQL timestamp is a very important data type, which can store date, time or date plus time. In the actual development process, rational use of timestamps can improve the efficiency of database operations and facilitate time-related queries and calculations. This article will discuss the functions, features, and application scenarios of MySQL timestamps, and explain them with specific code examples.

1. Functions and features of MySQL timestamps

There are two types of timestamps in MySQL, one is TIMESTAMP and the other is DATETIME . They have different functions and characteristics, which are introduced below:

1. TIMESTAMP:

   • The storage range is from 1970- 01-01 00:00:01 UTC to 2038-01-19 03:14:07 UTC.
   • The stored time will be converted to UTC time according to the time zone for storage.
   • When a new piece of data is inserted, the TIMESTAMP column will automatically update to the current timestamp.

2. DATETIME：

   • The storage range is 1000-01-01 00:00:00 to 9999-12-31 23:59:59.
   • will not be converted according to the time zone, and the actual inserted date and time will be stored.
   • When inserting data, it will not be automatically updated to the current time and needs to be set manually.

2. Application scenarios

1. Record the creation time and update time of data:

   CREATE TABLE example_table (
       id INT PRIMARY KEY AUTO_INCREMENT,
       data VARCHAR(255),
       created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
       updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
   );

   In this example, we create a table that records the creation time and update time of the data. By setting the created_at column to DEFAULT CURRENT_TIMESTAMP, the current timestamp is automatically recorded when inserting data; and setting the updated_at column to DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP, then update the timestamp when the data is updated.

2. Query data within the specified time range:

   SELECT * FROM example_table WHERE created_at >= '2022-01-01 00:00:00' AND created_at &lt ;= '2022-12-31 23:59:59';

   This query statement will return data records created in 2022. Time range queries can be easily performed using timestamps.

3. Calculation time interval:

   SELECT TIMEDIFF('2022-01-01 12:00:00', '2022-01-01 08:00:00' );

   This query statement will return the time interval between two timestamps, which can be used to calculate the difference between two dates and times.

3. Summary

MySQL timestamp is a very practical data type that can help us record the time information of data, perform time range queries, calculate time intervals, etc. operate. Proper use of timestamps can improve the efficiency of database operations and facilitate data management and analysis. I hope this article will help readers understand the functions, features and application scenarios of MySQL timestamps.

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