Detect if a date is in Daylight saving time in MySql

Question

I have inherited a legacy application where all the dates and times are stored in the local timezone (UK). I am not in a position to change how these are stored.

Howeve

Answer 1

You're in UK. So, your TZ should be CET or CEST (Central Europe Summer Time). You can get the info out this way:

mysql> SELECT @@system_time_zone;
+--------------------+
| @@system_time_zone |
+--------------------+
| CEST               |
+--------------------+

I use this in many of my Stored Procedures. Note: I need both forms of TZ info, whether I need to compute offsets with or without DST being applied.

CASE @@system_time_zone
  WHEN 'CET'  THEN SET l_tz = 'Europe/Paris';   SET l_tzOff = '+1:00';
  WHEN 'CEST' THEN SET l_tz = 'Europe/Paris';   SET l_tzOff = '+1:00';
  WHEN 'SGT'  THEN SET l_tz = 'Asia/Singapore'; SET l_tzOff = '+8:00';
  ELSE             SET l_tz = 'Europe/Paris';   SET l_tzOff = '+1:00';
END CASE;

You can get some inspiration from this.