Single column fetch returning in list in python postgresql

Question

Database:

id	trade	token
1	abc	5523
2	fdfd	5145
3	sdfd	2899

Code:

def db_fetchquery(sql):
    conn    = psycopg2.connect(database="trade", user='postgres', password='jps', host='127.0.0.1', port= '5432')
    cursor = conn.cursor()
    conn.autocommit = True
    cursor.execute(sql)
    row = cursor.rowcount
    if row >= 1:
        data = cursor.fetchall()
        conn.close()
        return data
    conn.close()
    return False

print(db_fetchquery("SELECT token FROM script"))

Result:

[(5523,),(5145,),(2899,)]

But I need results as:

[5523,5145,2899]

I also tried print(db_fetchquery("SELECT zerodha FROM script")[0]) but this gave result as:- [(5523,)]

Also, why is there ‘,’ / list inside list when I am fetching only one column?

Asked By: bowih

||

Source

Answer 1

Not sure if you are able to do that without further processing but I would do it like this:

data = [x[0] for x in data]

which convert the list of tuples to a 1D list

Answered By: Murtada Altarouti

Answer 2

To convert [(5523,),(5145,),(2899,)] to [5523, 5145, 2899] you can use lambda or list comprehension

using lambda

res = [(5523,),(5145,),(2899,)]
res = list(map(lambda x: x[0], res)) 
print(res) 
#output: [5523, 5145, 2899]

using list comprehension

res = [(5523,),(5145,),(2899,)]
res = [i[0] for i in res]
print(res) 
#output: [5523, 5145, 2899]

Answered By: Miraj

Single column fetch returning in list in python postgresql

Question:

Answers: