Postgresql table update

Question

I updated a database table using postgresql from python My code was

import psycopg2
connection=psycopg2.connect("dbname=homedb user=ria")
cursor=connection.cursor()
l_dict= {'licence_id':1}
cursor.execute("SELECT * FROM im_entry.usr_table")
rows=cursor.fetchall()

for row in rows:
   i=i+1
   p = findmax(row)
   #print p
   idn="id"
   idn=idn+str(i)


   cursor.execute("UPDATE im_entry.pr_table SET (selected_entry) = ('"+p+"') WHERE  image_1d ='"+idn+"'")
   print 'DATABASE TO PRINT'
cursor.execute("SELECT * FROM im_entry.pr_table")
rows=cursor.fetchall()
for row in rows:
    print row

I got the updated table displayed

But when i display updated table by psql as homedb=# SELECT * FROM im_entry.pr_table; i got an empty table displayed..what is wrong?? please help me

I solved it myself..I have forgotten to use COMMIT with in the procedure after INSERT and UPDATE statement in order to COMMIT the changes that were made!! — Ria
– Ria, Commented Mar 17, 2011 at 13:01
What does the findmax() function do exactly? I don't think the loop is necessary at all but that depends on what findmax() is doing — user330315
– user330315, Commented Mar 17, 2011 at 13:05

Community · Accepted Answer · 2017-05-23 12:17:14Z

7

You're probably not committing the transaction, i.e. you need a connection.commit() after all your updates.

There are various different settings you can make to the isolation level, e.g. autocommit, so you don't need to issue commits yourself. See, for example, How do I do database transactions with psycopg2/python db api?

edited May 23, 2017 at 12:17

CommunityBot

11 silver badge

answered Mar 17, 2011 at 13:03

seb

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