How to Convert UNIX Timestamps to DateTime in SQL Server?

SQL Server: Converting UNIX Timestamps to DateTime

UNIX timestamps, stored as bigint values, represent seconds elapsed since the Unix epoch (January 1, 1970, 00:00:00 UTC). Converting these to SQL Server's DATETIME format simplifies database management.

A straightforward method uses DATEADD:

<code class="language-sql">SELECT DATEADD(second, [unixtime], '19700101')
FROM [Table];</code>

This adds the unixtime (from the [unixtime] column) to the epoch date, yielding the corresponding DATETIME.

Understanding the Epoch

'19700101' represents the epoch – the origin point of the UNIX timestamp system. Adding the timestamp to this date effectively translates the numerical timestamp into a human-readable date and time.

Addressing the Year 2038 Problem

DATEADD's integer limitation (maximum 2,147,483,647 seconds) presents a challenge for timestamps exceeding this value. To handle dates beyond the year 2038, a more robust approach is needed, potentially involving splitting the timestamp into year and remaining seconds components for separate DATEADD operations. This avoids arithmetic overflow errors.

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