MySQL has system timezone, global timezone and session timezone (also call as per request timezone).

System timezone is current machine's timezone.
Global timezone and session timezone default value is system timezone.

When user insert a value to timestamp column (we call "date1"), MySQL suppose date1 as session timezone and convert to global timezone then save to DB.

When user select timestamp column, MySQL will convert from global timezone to session timezone than return value.

Just run this command and copy all results:

describe table_name;

Or if need more infomation about structure:

SELECT * from information_schema.columns
WHERE table_schema = 'database_name'
AND table_name = 'table_name';

Or export to file:

SELECT * from information_schema.columns
WHERE table_schema = 'database_name'
AND table_name = 'table_name'
INTO OUTFILE '/tmp/export.csv'
FIELDS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '"'
ESCAPED BY '\\'
LINES TERMINATED BY '\n';

From

SUM(column) as total

to

SUM(IFNULL(column, 0)) as total

Error "Numeric value out of range" when calculate with unsigned column and result is negative. Solution is CAST column to signed before calculate:

SUM(column1 - column2) as total

to

SUM(CAST(column1 AS SIGNED) - CAST(column2 AS SIGNED)) as total