Dear elco,

First of all, your external data (database) must be readable by excel. Such
as Ms Excel, Ms Access, & many to be named.

You may try to import data. MenuDataImport External DataNew Database
Query then choose your valid database.

Second, you may enter formula manually for each required cell by using
{SUMIF}; if your data in Ms Excel.
Code: SUMIF(range,criteria,sum_range)

range: where data to determine in criteria
criteria: selection data (in your case date)
sum_range: your data to sum

my ie: =sumif(<my data date,<my selection date,<my data amount)

That's all I can point you right now ^_^