howto: search for values in a range of cells where the range is depending on a comparison

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hi,

i can not seem to find a solution for this. thank you in advance for tips or links to a solution. the situation is as follows:

i have 3 tables that are connected through different cells. i give an example:

table1:
patient, age
1, 36
2, 67
3, 43

table 2 (patient occur more than once because of different time points of diagnosis):
patient, diagnosis
1, a
1, c
1, c
2, a
2, d
3, c

table 3:
diagnosis_needs_treatment
c
d
e
f

i now would like to combine the information in the three tables. i would like to add a field to table one that indicates if a patient had a diagnosis that needs treatment. later on, i further want to analyse the age of the patients that need treatment (but this is not important now). i want to end up with a table like this:

result_table
patient, age, needs_treatment
1, 36, yes
3, 43, yes

patient 2 could have a "no" or could be missing. that does not matter.

is this possible with built-in funtions?

thanks
m