We Keep Coding

Python: No of rows are always 9 and does not return affected rows count after UPDATE query

This is not something complicated but not sure why is it not working
import mysql.connector
def get_connection(host, user, password, db_name):
connection = None
try:
connection = mysql.connector.connect(
host=host,
user=user,
use_unicode=True,
password=password,
database=db_name
)
connection.set_charset_collation('utf8')
print('Connected')
except Exception as ex:
print(str(ex))
finally:
return connection
with connection.cursor() as cursor:
sql = 'UPDATE {} set underlying_price=9'.format(table_name)
cursor.execute(sql)
connection.commit()
print('No of Rows Updated ...', cursor.rowcount)
It always returns 0 no matter what. The same query shows correct count on TablePlus
MysQL API provides this method but I do not know how to call it as calling against connection variable gives error

I am not sure why your code does not work. But i am using pymysql, and it works
import os
import pandas as pd
from types import SimpleNamespace
from sqlalchemy import create_engine
import pymysql
PARAM = SimpleNamespace()
PARAM.DB_user='yourname'
PARAM.DB_password='yourpassword'
PARAM.DB_name ='world'
PARAM.DB_ip = 'localhost'
def get_DB_engine_con(PARAM):
DB_name = PARAM.DB_name
DB_ip = PARAM.DB_ip
DB_user = PARAM.DB_user
DB_password = PARAM.DB_password
## engine = create_engine("mysql+pymysql://{user}:{pw}#{ip}/{db}".format(user=DB_user,pw=DB_password,db=DB_name,ip=DB_ip))
conn = pymysql.connect(host=DB_ip, user=DB_user,passwd=DB_password,db=DB_name)
cur = conn.cursor()
return cur, conn ## , engine
cur, conn = get_DB_engine_con(PARAM)
and my data
if i run the code
table_name='ct2'
sql = "UPDATE {} set CountryCode='NL' ".format(table_name)
cur.execute(sql)
conn.commit()
print('No of Rows Updated ...', cur.rowcount)
the result No of Rows Updated ... 10 is printed. and the NLD is changed to NL
If using mysql.connector
import mysql.connector
connection = mysql.connector.connect(
host=PARAM.DB_ip,
user=PARAM.DB_user,
use_unicode=True,
password=PARAM.DB_password,
database=PARAM.DB_name
)
cur = connection.cursor()
table_name='ct2'
sql = "UPDATE {} set CountryCode='NL2' ".format(table_name)
cur.execute(sql)
print('No of Rows Updated ...', cur.rowcount)
connection.commit()
it still works
and the country code is updated to NL2 and No of Rows Updated ... 10 is printed. The second time i run then No of Rows Updated ... 0 is printed.
Not sure why it does not work on your machine.

Executing multiple MySQL SELECT queries python

I need to execute multiple MySQL select queries in Python. I am thinking of doing it in this way:
connection = mysql.connector.connect(host = HOSTNAME, user = USERNAME, passwd = PASSWORD, db = DATABASE, port=PORT)
cursor = connection.cursor()
try:
query_table0 = 'SELECT %s FROM %s'%(COLUMN.get(TABLES[0]),TABLES[0])
query_table1 = 'SELECT %s FROM %s'%(COLUMN.get(TABLES[1]),TABLES[1])
query_table2 = 'SELECT %s FROM %s'%(COLUMN.get(TABLES[2]),TABLES[2])
cursor.execute(query_table0)
result_table0 = cursor.fetchall()
cursor.execute(query_table1)
result_table1 = cursor.fetchall()
cursor.execute(query_table2)
result_table2 = cursor.fetchall()
finally:
connection.close()
Is there any more optimised way of executing multiple SQL statements in Python?

Pyodbc- If table exist then don't create in SSMS

I am trying something like:
import pyodbc
cnxn = pyodbc.connect(driver ='{SQL Server}' ,server ='host-MOBL\instance',database ='dbname', trusted_connection = 'yes' )
cursor = cnxn.cursor()
cursor.execute("""SELECT * FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_NAME = N'TableName'""")
def checkTableExists(cnxn, TableName):
cursor = cnxn.cursor()
cursor.execute("""
SELECT COUNT(*)
FROM information_schema.tables
WHERE TABLE_NAME = '{0}'
""".format(TableName.replace('\'', '\'\'')))
if cursor.fetchone()[0] == 1:
cursor.close()
return True
cursor.close()
return False
if checkTableExists == True:
print ("already")
elif checkTableExists == False:
print ("No")
But there is nothing happen, can anyone help me on this?
I am using Micrsoft SQL Server Management Studio 2014 Express version.
The code will be run in Python.
Thank you

Use the built-in Cursor.tables method for this check - following code sample assumes connection and cursor are instantiated
if cursor.tables(table='TableName', tableType='TABLE').fetchone():
print("exists")
else:
print("doesn't exist")
Note this isn't functionally different from querying INFORMATION_SCHEMA.TABLES, but allows code portability with different database platforms (and IMO improves readability).
Using SQL Server Native Client 11.0 and SQL Server 2014, calling Cursor.tables just executes the sp_tables system stored procedure.

Here's a simple example:
import pyodbc
conn = pyodbc.connect('DRIVER={FreeTDS};SERVER=yourserver.com;PORT=1433;DATABASE=your_db;UID=your_username;PWD=your_password;TDS_Version=7.2;')
cursor = conn.cursor()
cursor.execute("""
IF EXISTS (SELECT * FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME = N'your_table_name')
BEGIN
SELECT 'Your table exists.' AS result
END
""")
rows = cursor.fetchall()
for row in rows:
print(row.result)
That prints "Table Exists" for me. You should be able to modify it to your needs.

Return a mapped dictionary based on multiple queries

Issue: I can't figure out how to run a query in the correct way so that it returns a mapped dictionary. The query will use counts from multiple tables.
I am using psycopg2 for a postgresql database, and I will be using the results to create a report on day to day deltas on these counts.
Given that, can someone provide an example on how to execute multiple queries and return a dictionary that I can use for comparison purposes? Thanks! I image in a for loop is needed somewhere in here.
tables = ['table1', 'table2']
def db_query():
query = "select count(*) from (a_table) where error_string != '';"
conn = psycopg2.connect(database=db, user=user, password=password, host=host)
cur = conn.cursor(cursor_factory=psycopg2.extras.DictCursor)
cur.execute(query, tables)
output = cur.fetchall()
conn.close()
return output

I haven't used postgresql, so you might want to also check this out as a reference: How to store count values in python.
That being said, rearrange your code into something like this. Be sure to make conn global so you don't have to make more than one connection, and make sure you're also closing cur:
conn = None
def driverFunc():
global conn
try:
conn = psycopg2.connect(database=db, user=user, password=password, host=host)
tables = ['table1', 'table2']
countDict = {}
for thisTable in tables:
db_query(thisTable, countDict)
finally:
if not conn == None:
conn.close()
def db_query(tableName, countDict):
# Beware of SQL injection with the following line:
query = "select count(*) from " + tableName + " where error_string != '';"
cur = None
try:
cur = conn.cursor(cursor_factory=psycopg2.extras.DictCursor)
cur.execute(query)
countDict[tableName] = int(cur.fetchone())
finally:
if not cur == None:
cur.close()

is there a way to do a insert an request the scope_identity() using pyodbc to sql server 2005

I have this great pyodbc lib. I try the code below, it supposed to insert a row and return the row id but it didn't work. by the way I'm using sql server 2005 on server and client is windows os
...
con = pyodbc.connect('conectionString', autocommit = True)
cur = con.execute(
"insert into sometable values('something');
select scope_identity() as id"
)
for id in cur:
print id
...
some idea?

Try this, one statement with the OUTPUT clause
cur = con.execute(
"insert into sometable OUTPUT INSERTED.idcolumn values('something')"
)
row = cur.fetchone()
lastrowid = row[0]
Edit: This should get around the issue commented by Joe S.

Using SCOPE_IDENTITY() is the way to go as there are limitations and quirks using OUTPUT and ##IDENTITY because of triggers.
Using your code snipped, you just need to add a call to nextset to get the id.
...
con = pyodbc.connect('conectionString', autocommit = True)
cur = con.execute(
"insert into sometable values('something');
select scope_identity() as id"
)
cur.nextset()
for id in cur:
print id
...