Query where column match one or all, according to an argument

Question

Sorry if this is basic. I have a function that get as an argument one of these 2 :

subjects ['ALL']. //search for any subject
subjects ['A','B','C'] //only one of these

So in my function I need to query according to subjects argument

def function (subjects):
 
 query = ('''
 SELECT date_num, subject, in_col
 FROM base
 WHERE subject in {subjects} // = subject in ('A','B','C') works, but what about ALL ?
 ''').format(subjects=subjects)

so when the subjects to be found are a,b,c there is no problem, but how can I tell it to search for ALL subjects in the case argument is ALL ?

Could I send * instead ? like subjects[*] ?

(I do turn the ['a','b'] into ('a','b') in my code )

• user2261062: just don't add the where clause.
• matszwecja: How about dropping the whole "WHERE ..." part altogether?
• baltiturg: sorry can you show me ? I need to have the same single function for both cases, if I drop it how can specify for the case of a,b,c only ? thanks.
• pringi: Does this answer your question? Creating a dynamic SQL Query from Python
• baltiturg: @SembeiNorimaki so how can I satisfy both cases? like a,b,c or ALL in the same function ?

Answer 1

subjects = ['ALL']
# subjects = ['A', 'B']
where_clause = f"WHERE subject in {tuple(subjects)}" if subjects[0] != "ALL" else ""
query = f'''SELECT date_num, subject, in_col FROM base {where_clause}'''

Try uncommenting the second line to check how the query modifies

Answer 2

Create a generic query and add the where clause if needed

query = "SELECT date_num, subject, in_col FROM base"
if subjects[0] != "ALL":
 query += f" WHERE subject in {subjects}"