Updating entire column with data from tuple in PostgreSQL(psycopg2) - python-2.7

Question

First of all, there is my script:
import psycopg2
import sys
data = ((160000,),
(40000,),
(75000,),
)
def main():
try:
connection = psycopg2.connect("""host='localhost' dbname='postgres'
user='postgres'""")
cursor = connection.cursor()
query = "UPDATE Planes SET Price=%s"
cursor.executemany(query, data)
connection.commit()
except psycopg2.Error, e:
if connection:
connection.rollback()
print 'Error:{0}'.format(e)
finally:
if connection:
connection.close()
if __name__ == '__main__':
main()
This code works of course, but not in the way I want. It updates entire column 'Price' which is good, but it updates it only by use of the last value of 'data'(75000).
(1, 'Airbus', 75000, 'Public')
(2, 'Helicopter', 75000, 'Private')
(3, 'Falcon', 75000, 'Military')
My desire output would look like:
(1, 'Airbus', 160000, 'Public')
(2, 'Helicopter', 40000, 'Private')
(3, 'Falcon', 75000, 'Military')
Now, how can I fix it?

Answer 1

Without setting up your database on my machine to debug, I can't be sure, but it appears that the query is the issue. When you execute
UPDATE Planes SET Price=%s
I would think it is updating the entire column with the value being iterated on from your data tuple. Instead, you might need the tuple to a dictionary
({'name':'Airbus', 'price':160000}, {'name':'Helicopter', 'price':40000}...)
and change the query to
"""UPDATE Planes SET Price=%(price)s WHERE Name=%(name)s""".
See the very bottom of this article for a similar formulation. To check that this is indeed the issue, you could just execute the query once (cursor.execute(query)) and I bet you will get the full price column filled with the first value in your data tuple.