Adding Values To Columns

I have a table with 6 columns. which we can call a, b, c, d, e, f. What I want to achieve is to put data in column d and e and then split this result in column f.

The data I want to put in column d and e is already exported and executed from a table called exp_data, which is from a period of november.

So this is what i have so far but is not working:

update split_table set d =
select amount from exp_data
where period = '1111'
and exp_data.account = split_table.b
and exp_data.company = split_table.a

The error I get is incorrect syntax near select. Fixed the issue by adding a parenthesis before the select until the end...