Develop Reference

Why wont this loop?

Newby working my way through python and sql with mariadb.
Why wont this loop? It updates the first record only. Im pretty hack at this...
cursor1.execute("select recordid, mvavgvol, quote_usd_volume_change_24h from pumped")
records = cursor1.fetchall()
for x in records:
rid = (x[0])
m = (x[1])
o = (x[2])
if (m >= o):
result = 0
else:
result = 1
upd_data=(result,rid)
sql1 = ("UPDATE pumped SET mvavgvolcheck = %s WHERE recordid = %s")
cursor2.execute(sql1,upd_data)
conn.commit()

Since you are fetching multiple rows you have to store the fetched values in an array and use cursor's executemany() method instead.
✂
data= []
for x in records:
rid = (x[0])
result= int(x[1] > x[2])
data+= [(result, rid)]
cursor.executemany(UPDATE pumped SET mvavgvolcheck = %s WHERE recordid = %s", data);
✂
When using mariadb python module (MariaDB Connector/Python) this is much more effective since it reduces network traffic: instead of sending n update commands in a loop (where n is the number of rows in table pumped) only one command will be send to the server.

conn = msql.connect(host=Host,port=Port, user=User, password=Password, database=database)
cursor1 = conn.cursor()
cursor2 = conn.cursor()
cursor1.execute("select recordid, mvavgvol, quote_usd_volume_change_24h from pumped")
records = cursor1.fetchall()
for x in records:
rid = (x[0])
m = (x[1])
o = (x[2])
if (m >= o):
result = 0
cursor2.execute("UPDATE pumped SET mvavgvolcheck = %s WHERE recordid = %s",(result, rid))
conn.commit()
else:
result = 1
cursor2.execute("UPDATE pumped SET mvavgvolcheck = %s WHERE recordid = %s",(result, rid))
conn.commit()

Python code not creating tables on the database but able to query the results postgres

My usecase is to write create a temp table in the postgres database and fetch records from it and insert into a different table.
The code i used is:
import psycopg2
import sys
import pprint
from __future__ import print_function
from os.path import join,dirname,abspath
import xlrd
import os.path
newlist = []
itemidlist = []
def main():
conn_string = "host='prod-dump.cvv9i14mrv4k.us-east-1.rds.amazonaws.com' dbname='ebdb' user='ebroot' password='*********'"
# print the connection string we will use to connect
# print "Connecting to database" % (conn_string)
# get a connection, if a connect cannot be made an exception will be raised here
conn = psycopg2.connect(conn_string)
# conn.cursor will return a cursor object, you can use this cursor to perform queries
cursor = conn.cursor()
dealer_id = input("Please enter dealer_id: ")
group_id = input("Please enter group_id: ")
scriptpath = os.path.dirname('__file__')
filename = os.path.join(scriptpath, 'Winco - Gusti.xlsx')
xl_workbook = xlrd.open_workbook(filename, "rb")
xl_sheet = xl_workbook.sheet_by_index(0)
print('Sheet Name: %s' % xl_sheet.name)
row=xl_sheet.row(0)
from xlrd.sheet import ctype_text
print('(Column #) type:value')
for idx, cell_obj in enumerate(row):
cell_type_str = ctype_text.get(cell_obj.ctype, 'unknown type')
#print('(%s) %s %s' % (idx, cell_type_str, cell_obj.value))
num_cols = xl_sheet.ncols
for row_idx in range(0, xl_sheet.nrows): # Iterate through rows
num_cols = xl_sheet.ncols
id_obj = xl_sheet.cell(row_idx, 1) # Get cell object by row, col
itemid = id_obj.value
#if itemid not in itemidlist:
itemidlist.append(itemid)
# execute our Query
'''
cursor.execute("""
if not exists(SELECT 1 FROM model_enable AS c WHERE c.name = %s);
BEGIN;
INSERT INTO model_enable (name) VALUES (%s)
END;
""" %(itemid,itemid))
'''
cursor.execute("drop table temp_mbp1")
try:
cursor.execute("SELECT p.model_no, pc.id as PCid, g.id AS GROUPid into public.temp_mbp1 FROM products p, \
model_enable me, products_clients pc, groups g WHERE p.model_no = me.name \
and p.id = pc.product_id and pc.client_id = %s and pc.client_id = g.client_id and g.id = %s"\
% (dealer_id,group_id)
except (Exception, psycopg2.DatabaseError) as error:
print(error)
cursor.execute("select count(*) from public.temp_mbp1")
# retrieve the records from the database
records = cursor.fetchall()
# print out the records using pretty print
# note that the NAMES of the columns are not shown, instead just indexes.
# for most people this isn't very useful so we'll show you how to return
# columns as a dictionary (hash) in the next example.
pprint.pprint(records)
if __name__ == "__main__":
main()
The try except block in between the program is not throwing any error but the table is not getting created in the postgres database as i see in the data admin.
The output shown is:
Please enter dealer_id: 90
Please enter group_id: 13
Sheet Name: Winco Full 8_15_17
(Column #) type:value
[(3263,)]
Thanks,
Santosh

You didn't commit the changes, so they aren't saved in the database. Add to the bottom, just below the pprint statement:
conn.commit()

Error in using variables in SQL statement in Python?

I have the following Python code:
cursor = connection.cursor()
a = "C6DE6778-5956-48D4-BED6-5A2A37BBB123"
SQLCommand = ("""SELECT *
FROM Table
WHERE Table.ENUM = ?
""", a)
results = cursor.execute(SQLCommand)
The following error is returned:
TypeError: string or integer address expected instead of tuple instance

The way you constructed the sqlcommand is incorrect. Pass the parameter when you execute.
a = "C6DE6778-5956-48D4-BED6-5A2A37BBB123"
SQLCommand = """SELECT *
FROM Table
WHERE Table.ENUM = ?
"""
results = cursor.execute(SQLCommand,(a,))

SQLCommand is a tuple in your case. .execute() expects sql statement as the first argument. To rectify the error, you can do something like this :
cursor = connection.cursor()
a = "C6DE6778-5956-48D4-BED6-5A2A37BBB123"
SQLCommand = """SELECT *
FROM Table
WHERE Table.ENUM = '%s'
""" % a
results = cursor.execute(SQLCommand)
Alternatively, you can format you SQL statement string like this :
SQLCommand = """SELECT *
FROM Table
WHERE Table.ENUM = '{}'
""".format(a)
Or you can pass a as an optional parameter to .execute() like this :
cursor = connection.cursor()
a = "C6DE6778-5956-48D4-BED6-5A2A37BBB123"
SQLCommand = """SELECT *
FROM Table
WHERE Table.ENUM = ?
"""
print(SQLCommand, a)
You can refer to the documentation for more understanding on this.

How to pass a python variable to a MS SQL SELECT instruction?

Why this code returns nothing?
ip = '10.113.205.55'
cursor.execute("Select * from tablename WHERE ip like '%s' "), ip
result = cursor.fetchall()
print result
when i use the code below it works:
cursor.execute("Select * from tablename where ip like '10.113.205.55' ")
result = cursor.fetchall()
print result

You should remove the ' and put ip inside the parameter list:
cursor.execute("SELECT * FROM tablename WHERE ip LIKE %s", [ip])

change the argument of cursor.execute method to:cursor.execute("Select * from tablename WHERE ip like '%s'" % ip)

Python: how to pass string to postgres command using psycopg2

I have a problem passing a string to a query in python for postgresql. In particular I have the following script that works perfectly:
y = 'test'
for i in un:
crs = conn.cursor()
query = """
select *
FROM test
WHERE test.vin_id = %s
;"""
s_id = i
crs.execute(query,[s_id])
s_out = crs.fetchall()
but if I change test with the variable y it gives me an error.
for i in un:
crs = conn.cursor()
query = """
select *
FROM %s
WHERE %s.vin_id = %s
;"""
s_id = i
crs.execute(query,[y,y,s_id])
s_out = crs.fetchall()
ProgrammingError: syntax error at or near "'test'"
LINE 3: FROM 'test'

Unfortunately it does not work and I have the same problem when I try to put sentences in the middle, for instance:
query1 = """
SELECT *
FROM test1
WHERE %s LIKE '%' || vin_id || '%'
;"""
crs1 = conn.cursor()
crs1.execute(query1, [s_id])

You can use AsIs:
from psycopg2.extensions import AsIs
for i in un:
crs = conn.cursor()
query = """
select *
FROM %s
WHERE %s.vin_id = %s
;"""
s_id = i
crs.execute(query,[AsIs(y),AsIs(y),s_id])
s_out = crs.fetchall()