How to store timestamp in db and how to utilize timestamp in sql queries?

Answer 1

insert new column data type datetime to your table and set default getdate()
when insert query executes default set column take system date and time will be stored in that column u can use it like any other column ex your datetime column name is dtime then write select query like this
select dtime from mytable u can give a alias name for that column

Answer 2

and u don't have to pass value to that column😀 its a default column and also u can use that like any other column to update delete whatever you like

Answer 3

INSERT INTO TABLE NAME VALUES (SYSDATE) ;