TIMESTAMP indicates when each row in the table was last modified.
When a column is declared with DEFAULT TIMESTAMP, a default value is provided for insert and load operations. The value is updated with the current date and time whenever the row is updated.
On INSERT and LOAD, DEFAULT TIMESTAMP has the same effect as CURRENT TIMESTAMP. On UPDATE, if a column with a default value of TIMESTAMP is not explicitly modified, the value of the column is changed to the current date and time.