As per psycopg2 documentation the execute function takes variables as an extra parameter.
cursor.execute("""select * from table where type = %(value)s """, {"value": variable_value})
More examples in psycopg2 user manual..
Also please read carefully the section about SQL injection - the gist is, you should not quote parameters in your query, the execute function will take care of that to prevent the injection of harmful SQL.
Also to explain the error you are getting - the query you're sending is comparing two identifiers (type and variable_value). The table does not contain variable_value column, hence the error.
I believe, you intended to use string interpolation to construct the query, but you forgot the {}. It would work like this:
cursor.execute(f"""select * from table where type = '{variable_value}'""")
⚠️ but because of previously mentioned SQL injection, it is not a recommended way!.
Answer from botchniaque on Stack Overflowpython - Psycopg2 - Passing variable in the where clause - Stack Overflow
(Python psycopg) How do I add additional WHERE … AND … conditions to a SQL statement?
psycopg2 - Python/psycopg WHERE IN statement - Stack Overflow
postgresql - Python psycopg2 dynamic where clause with optional AND based on conditional - Stack Overflow
Using psycopg, I’d like to build a SQL statement according to certain conditions. There would be a base SELECT query, and then append WHERE. And then append AND. And then append another AND, etc.
I appreciate help on this!
For the IN operator, you want a tuple instead of list, and remove parentheses from the SQL string.
# using psycopg2
data=('UK','France')
sql='SELECT * from countries WHERE country IN %s'
cur.execute(sql,(data,))
During debugging you can check that the SQL is built correctly with
cur.mogrify(sql, (data,))
To expland on the answer a little and to address named parameters, and converting lists to tuples:
countryList = ['UK', 'France']
sql = 'SELECT * from countries WHERE country IN %(countryList)s'
cur.execute(sql, { # You can pass a dict for named parameters rather than a tuple. Makes debugging hella easier.
'countryList': tuple(countryList), # Converts the list to a tuple.
})