How can I change the timezone in MySQL? In a MySQL DB, I have two varchar fields. One is for date and one is for time. I need to change the time from CST to GMT. In MySQL how do we convert the combination of these date and time fields from CST to GMT time? It could be helpful if I get some sample queries for retrieve the same.
You would use the CONVERT_TZ function like this:

SELECT CONVERT_TZ('2012-01-01 12:00:00','-06:00','+00:00')


Example SQL Fiddle

But, why are you using varchar for your date/time fields? It would be better to use the proper data types DATE and TIME.