Fill percentage of total field conditional on some other field with MS Access SQL

This question is an extension of [Fill percentage of total field with MS Access SQL](https://dba.stackexchange.com/questions/156749/fill-percentage-of-total-field-with-ms-access-sql) . I have the following 2013 MS Access SQL query: UPDATE MyTable SET F = f / DSUM("f", "MyTable") ; This query fills field F with the percentage over the total of some field f, such that each one of the records F(i) in field F is given by: F(i) = f(i)/SUM_i(f(i)) Both fields f and F belong to table MyTable. Now, I would like, instead of simply computing the percentage over the whole table, to do it by Date, where Date is a 3rd field also to be found in table MyTable. I will make up an example for illustration purposes. Let's assume a simplified MyTable with 2 records per date; then that's what I would like MyTable to look like after executing my desired query... - see fields f and F: | Date | Department | f | F | |------------|------------|-----------|-----------| | t1 | D1 | 2 | 40% | | t1 | D2 | 3 | 60% | | t2 | D1 | 1 | 20% | | t2 | D2 | 4 | 80% | ... And this is how it is looking right now, after executing the query displayed above: | Date | Department | f | F | |------------|------------|-----------|-----------| | t1 | D1 | 2 | 20% | | t1 | D2 | 3 | 30% | | t2 | D1 | 1 | 10% | | t2 | D2 | 4 | 40% | I have tried the following code, but none yielded what I wanted. _Try #1_: UPDATE MyTable SET F = f / DSUM("f", "MyTable", "Date"); _Try #2_: UPDATE MyTable SET F = f / DSUM("f", "MyTable", "Date=Date"); Any ideas on how I could manage to do this? **Note**: I have just called the two fields "f" and "F" here for illustration purposes, it is not how they are named in the actual DB. ---------- I will add here further tests that haven't worked out: _Try #3_: UPDATE MyTable SET F = f / DSUM("f", "MyTable", "Date=" & Date); _Try #4_: this has worked but only for a single Date, the 1st one to be recorded - i.e. the one in the 1st row/record of the table MyTable - for the rest of dates the value for F is empty. UPDATE MyTable SET F = f / DSUM("f", "MyTable", "Date=#" & Date & "#");