Analysis of the principle and implementation mechanism of MySQL timestamp
Analysis of the principle and implementation mechanism of MySQL timestamp
In the MySQL database, timestamp (Timestamp) is a data type used to store date and time information . It can record the number of seconds of the timestamp, accurate to the microsecond level, and is used to record information such as the creation time or last update time of data in the database. This article will analyze the principles and implementation mechanisms of MySQL timestamps and provide specific code examples.
1. The principle of MySQL timestamp
In MySQL, the timestamp is stored starting from the moment "1970-01-01 00:00:00" Number of seconds to record time. This is called a "Unix timestamp" and is a commonly used method of representing time. MySQL will automatically convert the timestamp internally, convert it to UTC time when storing, and then convert it to local time based on time zone and other information when querying.
It is worth noting that there are two types of timestamps in MySQL: TIMESTAMP
and DATETIME
. They differ slightly in how they are stored. TIMESTAMP
will be affected by the time zone when storing, while DATETIME
is not affected by the time zone, and the stored time is accurate to seconds.
2. MySQL timestamp implementation mechanism
MySQL uses system time to generate and store timestamps. When recording data, if the column type is defined as TIMESTAMP
, MySQL will automatically assign the current timestamp to the column when a record is inserted. For the DATETIME
type, you need to manually assign a timestamp to the column.
The following is a specific MySQL code example to illustrate the implementation mechanism of timestamp:
--Create a table containing columns of TIMESTAMP and DATETIME types CREATE TABLE logs ( log_id INT PRIMARY KEY, log_content VARCHAR(255), created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP, -- TIMESTAMP type automatically assigns the current time modified_at DATETIME -- requires manual assignment ); --Insert a record INSERT INTO logs (log_id, log_content) VALUES (1, "Hello World"); -- Query the records SELECT * FROM logs;
The above code creates a table named logs
, including log_id
, log_content
, created_at
and modified_at
four columns, of which created_at
is listed as TIMESTAMP
type and modified_at
is listed as DATETIME
type . When inserting a record, the created_at
column will be automatically assigned the current timestamp, while the modified_at
needs to be assigned manually.
3. Summary
This article analyzes the principle and implementation mechanism of MySQL timestamp, and introduces the storage method of timestamp and its application in MySQL. By using columns of the TIMESTAMP
and DATETIME
types, you can easily record the time information of the data, and perform operations such as searching and comparing timestamps as needed. I hope this article will help you understand MySQL timestamps!
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