Return KDB query to a pandas dataframe

Question

I would like to extract data from a KDB database and place into a dataframe. My query runs fine in qpad, no issues; just need to write it into my Pandas dataframe. My code:

from qpython import qconnection

# Create the connection and save the handle to a variable
q  = qconnection.QConnection(host = 'wokplpaxvj003', port = 11503, username = 'pelucas', password = 'Dive2600', timeout = 3.0)
try:
    # initialize connection
    q.open()
    print(q)
    print('IPC version: %s. Is connected: %s' % (q.protocol_version, q.is_connected()))

    df = q.sendSync('{select from quote_flat where date within (2019.08.14;2019.08.14), amendment_no = (max;amendment_no)fby quote_id}')

    df.info()

finally:
    q.close()

It fails on the df.info() raising AttributeError: 'QLambda' object has no attribute 'info' so I guess the call is not successful.

Answer 1

It looks like you've sent only a lambda but with no instruction to execute that lambda. Two options:

1. Don't make it a lambda

df = q.sendSync('select from quote_flat where date within (2019.08.14;2019.08.14), amendment_no = (max;amendment_no)fby quote_id')

2. Execute the lambda

df = q.sendSync('{select from quote_flat where date within (2019.08.14;2019.08.14), amendment_no = (max;amendment_no)fby quote_id}[]')