mysql select UNIXTIME

MySQL SELECT UNIXTIME

Introduction

In MySQL, the UNIX_TIMESTAMP() function is used to get the current Unix timestamp. This timestamp represents the number of seconds that have elapsed since January 1, 1970, at 00:00:00 UTC. However, if you have stored timestamps in your database as Unix timestamps, you may need to convert them back to a human-readable format for better understanding.

In this article, we will explore how to use the UNIX_TIMESTAMP() function in combination with the FROM_UNIXTIME() function to retrieve and convert Unix timestamps in MySQL. We will also cover some practical examples and demonstrate how to use these functions effectively.

Syntax

The syntax for the UNIX_TIMESTAMP() function is as follows:

UNIX_TIMESTAMP([date])

Here, date is an optional parameter that represents the date or datetime value to be converted to a Unix timestamp. If no parameter is specified, the current date and time are used.

The syntax for the FROM_UNIXTIME() function is as follows:

FROM_UNIXTIME(unix_timestamp, [format])

Here, unix_timestamp is the Unix timestamp value that needs to be converted to a readable date or time format. The format parameter is optional and allows you to specify the output format. If no format is specified, the default format is '%Y-%m-%d %H:%i:%s'.

Examples

Let's consider a table called users with the following structure:

Column	Type
id	INT
name	VARCHAR(100)
created_at	INT

We want to retrieve the name and created_at columns from the users table, where created_at is stored as a Unix timestamp. We also want to convert the Unix timestamp to a readable date format.

To achieve this, we can use the following SQL query:

SELECT name, FROM_UNIXTIME(created_at) AS created_date FROM users;

In this query, we are using the FROM_UNIXTIME() function to convert the created_at column to a readable date format. The AS keyword is used to alias the converted date as created_date in the result set.

Additionally, if you want to specify a custom format for the output, you can use the format parameter of the FROM_UNIXTIME() function. For example:

SELECT name, FROM_UNIXTIME(created_at, '%Y-%m-%d') AS created_date FROM users;

This query will return the name column and the created_at column converted to the format 'YYYY-MM-DD'.

Conclusion

In this article, we have learned how to use the UNIX_TIMESTAMP() function to retrieve Unix timestamps from a MySQL database and the FROM_UNIXTIME() function to convert them back to a human-readable format. We have also seen examples of how these functions can be used effectively in SQL queries.

By understanding and using these functions, you can work with Unix timestamps more efficiently and convert them to a format that is easier to interpret and analyze.