What happens when you insert nothing after declaring a column “timestamp default CURRENT_TIMESTAMP”?

In this case, the current timestamp gets inserted into the table column. Let us first create a table −

mysql> create table DemoTable
(
   ArrivalDate timestamp default CURRENT_TIMESTAMP
);
Query OK, 0 rows affected (0.55 sec)

Insert some records in the table using insert command −

mysql> insert into DemoTable values(now());
Query OK, 1 row affected (0.14 sec)
mysql> insert into DemoTable values();
Query OK, 1 row affected (0.13 sec)

Display all records from the table using select statement −

mysql> select *from DemoTable;

This will produce the following output −

+---------------------+
| ArrivalDate         |
+---------------------+
| 2019-09-01 14:08:47 |
| 2019-09-01 14:08:50 |
+---------------------+
2 rows in set (0.00 sec)