How to get rid of a comma?

Question

import sqlite3

conn = sqlite3.connect('contacten.db')

c = conn.cursor()

#c.execute("""CREATE TABLE mail (
#           mail text
#           )""")

#c.execute("INSERT INTO mail VALUES ('[email protected]')")

conn.commit()

c.execute("SELECT * FROM mail")

print(c.fetchall())

conn.commit()
conn.close()

This is the code I've made but as a result, I get:

[('[email protected]',), ('[email protected]',), ('[email protected]',)]

But in this array I have a comma too much. ,), like this. does anyone of you know how to get rid of this extra comma?

c.fetchall() returns a list of lists... it's normal to be separated with commas — mlwn, Mar 21 '20 at 12:37
The comma is just part of the representation of a single-element tuple, not part of the data itself. — chepner, Mar 21 '20 at 12:44

Óscar López · Answer 1 · 2020-03-21T12:58:10.600

The commas are there for a good reason, your result is a list of tuples; this is a consequence of how sqlite represents the result set, the data itself doesn't contain commas:

result = c.fetchall()
print(result)
=> [('[email protected]',), ('[email protected]',), ('[email protected]',)]

That's because each row can have more than one field. In your case you only have one field, but Python can't just remove the comma, because if we did you'd end up with a list of elements between brackets, not a list of tuples (see here to understand why).

Of course, if you're certain that the result will only have one field per row, you can simply get rid of the tuples by extracting the one (and only) field from each row at the moment of printing the result:

result = c.fetchall()
print([f[0] for f in result])
=> ['[email protected]', '[email protected]', '[email protected]']

Or use unpacking: `[f for f, in result]` – Kelly Bundy Mar 21 '20 at 12:53 — Kelly Bundy, Mar 21 '20 at 12:53

score 2 · Answer 2 · answered Mar 21 '20 at 12:55

Using python zip:

>>> emails = [('[email protected]',), ('[email protected]',), ('[email protected]',)]
>>> emails, = zip(*emails)
>>> type(emails)
<type 'tuple'>
>>> emails
('[email protected]', '[email protected]', '[email protected]')
>>> list(emails)
['[email protected]', '[email protected]', '[email protected]']

score 0 · Answer 3 · answered Mar 21 '20 at 12:42

import sqlite3                                                                                      

conn = sqlite3.connect('contacten.db')                                                              

c = conn.cursor()                                                                                   

#c.execute("""CREATE TABLE mail (                                                                       
#           mail text                                                                               
#           )""")                                                                                   
#c.execute("INSERT INTO mail VALUES ('[email protected]')")                                            
#c.execute("INSERT INTO mail VALUES ('[email protected]')")                                           
#c.execute("INSERT INTO mail VALUES ('[email protected]')")                                           

conn.commit()                                                                                       

c.execute("SELECT * FROM mail")                                                                     

#print(c.fetchall())                                                                                

for item in c.fetchall():                                                                           
    print item[0]                                                                                   

conn.commit()                                                                                       
conn.close()

How to get rid of a comma?

3 Answers3