Why do I keep getting error code: 1136???

Hi Asmaa!

You should use parentheses for each record you insert in the table. You used only one pair of parentheses, so Workbench treats this as one record and it searches for 8 columns because you have 8 records separated by comma in this one pair of parentheses. Since, you provide only two columns, error 1136 occurs.
Please, use the following code:
insert into dept_manager_dup (
emp_no,
from_date
) values
(999904, '2017-01-01'),
(999905, '2017-01-01'),
(999906, '2017-01-01'),
(999907, '2017-01-01');

Hope this helps.
Best,
Tsvetelin