Python psycopg2 cursor.fetchall() returns empty list but cursor.rowcount is > 1

问题

I am getting an issue here:

conn = psycopg2.connect(conn_string)
cursor = conn.cursor()

sql = """
    SELECT DISTINCT (tenor_years) 
    FROM bond_pnl 
    WHERE country = '%s'
""" % country

cursor.execute(sql)
print(cursor.fetchall())
print(cursor.rowcount)

It gives the following output:

[]
11

which means that cursor.rowcount is 11 but cursor.fetchall() is empty list. I have already tried doing this:

conn.set_session(readonly=True, autocommit=True)

and this solution as well :Click to see

Any help regarding this will be appreciated.

EDIT: Just came across another thing, this code when executed first time, works fine. But executing it again(second, third, ...n execution) gives the above behavior.

回答1:

After trying different solution, I have figured out that the problem described in the question arises when I execute it in "Debugging Mode" in pycharm. But on the other hand if I execute the code in "Run Mode" in pycharm , it returns the right expected output (a list with 11 elements):

[a,b,c,d,e,f,g,h,i,j,k]

Not sure about the exact reason for it but somehow the cursor was breaking somewhere when run in "Debugging Mode". If anyone describes the exact reason, It ll be highly appreciated.

来源：https://stackoverflow.com/questions/46273972/python-psycopg2-cursor-fetchall-returns-empty-list-but-cursor-rowcount-is-1