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The Code is not working in jupyter and giving the error as pictured below [duplicate]

I am trying to query on a local MySQL database using Python's (3.4) MySQL module with the following code:
class databases():
def externaldatabase(self):
try:
c = mysql.connector.connect(host="127.0.0.1", user="user",
password="password", database="database")
if c.is_connected():
c.autocommit = True
return(c)
except:
return(None)
d = databases().externaldatabase()
c = d.cursor()
r = c.execute('''select * from tbl_wiki''')
print(r)
> Returns: None
As far as I can tell, the connection is successful, the database is composed of several rows but the query always returns the none type.
What instances does the MySQL execute function return None?

Query executions have no return values.
The pattern you need to follow is:
cursor creation;
cursor, execute query;
cursor, *fetch rows*;
Or in python:
c = d.cursor()
c.execute(query) # selected rows stored in cursor memory
rows = c.fetchall() # get all selected rows, as Barmar mentioned
for r in rows:
print(r)
Also some db modules allow you to iterate over the cursor using the for...in pattern, but triple-check that regarding mysql.

For my case, I return the cursor as I need the value to return a string specifically, for instance, I return the password (string) for inspect whether user used the same password twice. Here's how I did it (In my case):
def getUserPassword(metadata):
cursorObject.execute("SELECT password FROM users WHERE email=%s AND password=%s LIMIT 1", (metadata['email'], metadata['password']))
return cursorObject.fetchall()[0]['password']
Which I can easily call from another class by calling the method:
assert getUserPassword({"email" : "email", "password" : "oldpass"}) is not None
And which the getUserPassword itself is returning a string

Search element from SQL using Python

I am writing a python script to perform some specific task if an element ID pre-exists. I have created a database where I am saving the data elements.
I want to find out if the element link_ID exists in the database or not. How will I do that?
I have written a small script which is not perfect. The output I am getting is No such element exists.
link_ID = link_1234
sql = ''' SELECT link_ID from link_table where link_ID=? '''
var = (link_ID)
conn.execute(sql, [var])
conn.commit()
if conn.execute(sql, [var]) == True:
print("Search Successful")
flag = 1
else:
print("No such element exists")
flag = 0

You have a number of problems here. First, you should create a cursor object from your connection and use that to execute your query:
c = conn.cursor()
c.execute(sql,var)
Secondly, execute wants a tuple of values to interpolate, not a list, so do this:
var = (link_ID,)
c.execute(sql,var)
Or:
c.execute(sql,(link_ID,))
Lastly, c.execute returns the cursor object rather than the success of the query. You should fetch the result of the query using fetchone(), if your query didn't return a row then the return value of fetchone() will be None:
result = c.fetchone()
if result is not None:
print('Success:',result)
else:
print('No row found for', link_ID)

python cursor.execute returning empty

I have a problem with my python code which I want to use for a REST API server.
The current problem is that my database query is returning null when I know that the value is there
The code for the specific path:
#app.route('/data/active_predicted/<int:ticketId>', methods=['GET'])
def search_db_tickId_act(ticketId):
cursor = db.cursor()
db_query = cursor.execute("select * from active_predicted where ticketId=" + str(ticketId))
json_output = json.dumps(dict(cursor.fetchall()))
cursor.close()
if not cursor.fetchall():
return "Nothing found \n SQL Query: " + "select * from active_predicted where ticketId=" + str(ticketId)
else:
return str(cursor.fetchall())
When I access this URL I get returned the following:
Nothing found SQL Query: select * from active_predicted where ticketId=1324
When I plug this SQL query I get the result I want, 1 row with 2 columns but it seems as though the program cannot locate the row?

The problems:
As #pvg mentioned, you need to escape your input values when querying database;
If you want to fetch a dictionary-like result, passing dictionary=True when you initialize the cursor;
In your original code, you didn't return the variable json_output;
To fetch only one result, use fetchone instead fetchall;
After cursor.close() got called, you can obtain nothing from that cursor no matter you fetched before or not;
Use try-finally to ensure that cursor always get closed (at last).
Here's the fixed code:
#app.route('/data/active_predicted/<int:ticketId>', methods=['GET'])
def search_db_tickId_act(ticketId):
try:
cursor = db.cursor(dictionary=True)
db_query = cursor.execute("select * from active_predicted where ticketId=%s LIMIT 1", ticketId)
row = cursor.fetchone()
if row:
return json.dumps(row)
else:
return "Nothing found \n SQL Query: " + "select * from active_predicted where ticketId=" + str(ticketId)
finally:
cursor.close()

python mysqldb, for loop not deleting records

Somewhere in here lies a problem. http://paste.pocoo.org/show/528559/
Somewhere between lines 32 and 37. As you can see the DELETE FROM is inside a for loop.
Running the script just makes the program go through the loop and exit, without actually removing any records.
Any help would be greatly appreciated! Thanks!
#!/usr/bin/env python
# encoding: utf-8
import os, os.path, MySQLdb, pprint, string
class MySQLclass(object):
"""Learning Classes"""
def __init__(self, db):
self.db=db
self.cursor = self.db.cursor()
def sversion(self):
self.cursor.execute ("SELECT VERSION()")
row = self.cursor.fetchone ()
server_version = "server version:", row[0]
return server_version
def getRows(self, tbl):
""" Returns the content of the table tbl """
statmt="select * from %s" % tbl
self.cursor.execute(statmt)
rows=list(self.cursor.fetchall())
return rows
def getEmailRows(self, tbl):
""" Returns the content of the table tbl """
statmt="select email from %s" % tbl
self.cursor.execute(statmt)
rows=list(self.cursor.fetchall())
return rows
def removeRow(self,tbl,record):
""" Remove specific record """
print "Removing %s from table %s" %(record,tbl)
print tbl
self.cursor.execute ("""DELETE FROM maillist_frogs where email LIKE %s""", (record,))
def main():
#####connections removed
sql_frogs = MySQLclass(conn_frogs)
sql_mailgust = MySQLclass(conn_mailgust)
frogs_emails = sql_frogs.getEmailRows ("emails")
frogs_systemcatch = sql_frogs.getEmailRows ("systemcatch")
mailgust_emails = sql_mailgust.getEmailRows ("maillist_frogs")
aa = set(mailgust_emails)
remove = aa.intersection(frogs_emails)
remove = remove.union(aa.intersection(frogs_systemcatch))
for x in remove:
x= x[0]
remove_mailgust = sql_mailgust.removeRow ("maillist_frogs",x)
conn_frogs.close ()
conn_mailgust.close ()
if __name__ == '__main__':
main()

the problem is python-msyqldb specific.:
Starting with 1.2.0, MySQLdb disables autocommit by default, as required by the DB-API standard (PEP-249). If you are using InnoDB tables or some other type of transactional table type, you'll need to do connection.commit() before closing the connection, or else none of your changes will be written to the database.
therefore, after the DELETE, you must self.db.commit

The removeRow() method does not return a value, yet remove_mailgust is expecting to receive this non-existent value.
Also, your removeRow() class method is statically fixed to only search the table maillist_frogs in its query. You should probably set the table name to accept the second parameter of the method, tbl.
Finally, your removeRow() method is comparing the value of a record (presumably, an id) using LIKE, which is typically used for more promiscuous string comparison. Is email your primary key in this table? If so, I would suggest changing it to:
self.cursor.execute ("""DELETE FROM %s where email_id = %s""", (tbl, record,))

TypeError: 'NoneType' object is not iterable

I need to process mysql data one row at a time and i have selected all rows put them in a tuple but i get the error above.
what does this mean and how do I go about it?

Provide some code.
You probably call some function that should update database, but the function does not return any data (like cursor.execute()). And code:
data = cursor.execute()
Makes data a None object (of NoneType). But without code it's hard to point you to the exact cause of your error.

It means that the object you are trying to iterate is actually None; maybe the query produced no results?
Could you please post a code sample?

The function you used to select all rows returned None. This "probably" (because you did not provide code, I am only assuming) means that the SQL query did not return any values.

Try using the cursor.rowcount variable after you call cursor.execute(). (this code will not work because I don't know what module you are using).
db = mysqlmodule.connect("a connection string")
curs = dbo.cursor()
curs.execute("select top 10 * from tablename where fieldA > 100")
for i in range(curs.rowcount):
row = curs.fetchone()
print row
Alternatively, you can do this (if you know you want ever result returned):
db = mysqlmodule.connect("a connection string")
curs = dbo.cursor()
curs.execute("select top 10 * from tablename where fieldA > 100")
results = curs.fetchall()
if results:
for r in results:
print r

This error means that you are attempting to loop over a None object. This is like trying to loop over a Null array in C/C++. As Abgan, orsogufo, Dan mentioned, this is probably because the query did not return anything. I suggest that you check your query/databse connection.
A simple code fragment to reproduce this error is:
x = None
for each i in x:
#Do Something
pass

This may occur when I try to let 'usrsor.fetchone' execute twice. Like this:
import sqlite3
db_filename = 'test.db'
with sqlite3.connect(db_filename) as conn:
cursor = conn.cursor()
cursor.execute("""
insert into test_table (id, username, password)
values ('user_id', 'myname', 'passwd')
""")
cursor.execute("""
select username, password from test_table where id = 'user_id'
""")
if cursor.fetchone() is not None:
username, password = cursor.fetchone()
print username, password
I don't know much about the reason. But I modified it with try and except, like this:
import sqlite3
db_filename = 'test.db'
with sqlite3.connect(db_filename) as conn:
cursor = conn.cursor()
cursor.execute("""
insert into test_table (id, username, password)
values ('user_id', 'myname', 'passwd')
""")
cursor.execute("""
select username, password from test_table where id = 'user_id'
""")
try:
username, password = cursor.fetchone()
print username, password
except:
pass
I guess the cursor.fetchone() can't execute twice, because the cursor will be None when execute it first time.

I know it's an old question but I thought I'd add one more possibility. I was getting this error when calling a stored procedure, and adding SET NOCOUNT ON at the top of the stored procedure solved it. The issue is that earlier selects that are not the final select for the procedure make it look like you've got empty row sets.

Try to append you query result to a list, and than you can access it. Something like this:
try:
cursor = con.cursor()
getDataQuery = 'SELECT * FROM everything'
cursor.execute(getDataQuery)
result = cursor.fetchall()
except Exception as e:
print "There was an error while getting the values: %s" % e
raise
resultList = []
for r in result:
resultList.append(r)
Now you have a list that is iterable.