I am making a database manager in Python and I want the user to be able to select a database.
I know that one can connect to a database using the following code
connection = pymysql.connect(
host='localhost'
user='root'
passwd=''
db='my_database'
)
But what if the user wants to connect to a different database later on? How would I tell connection to connect to a different database? Or better yet, omit db and then add it later on.
Calling pymysql.connect actually creates the connection to the database. If you want to connect to a different database you should create a new connection object, rather than trying to reuse the same one. You could assign it to the same variable name if you wanted to 'reuse' it later in your code.
Like this:
connection1 = pymysql.connect(
host='localhost'
user='root'
passwd=''
db='my_database'
)
connection2 = pymysql.connect(
host=?
user=?
passwd=?
db='my_other_database'
)
You can just do:
connection.close()
And then open another connection.
Related
I need to connect to the ms-sql database and then create a new database there using python script.
I have the user credentials for the login. So how to create the connection to the ms-sql server using python.
If you do not have database name then use the connection string as mentioned in the code below. Create a database after connection and use the database finally.
import pyodbc
# if you have user id and password then try with this connection string
connection_string = f"DRIVER={SQL Server};SERVER={server_name};UID={user_id};PWD={password}"
# if using in the local system then use the following connection string
connection_string = f"DRIVER={SQL Server};SERVER={server_name}; Trusted_Connection=True;"
connection= pyodbc.connect(connection_string)
cursor = connection.cursor()
sql_create_database = f"CREATE DATABASE {database_name}"
cursor.execute(sql_create_database)
set_database = f"USE {database_name}"
cursor.execute(set_database)
I have a code like this:
import mysql.connector as mysql
from generate_records import generateRecords
devicesQuery = "CALL iot.sp_sensors_overview()"
try:
db = mysql.connect(
user = "username",
password = "password",
host = "hostname",
database="iot"
)
cursor = db.cursor(dictionary=True, buffered=True)
cursor.execute(devicesQuery)
for sensor in cursor:
generateRecords(sensor, db)
cursor.close()
except mysql.connector.Error as error:
print("Error:")
print(error)
else:
db.close()
The purpose of generateRecords function is obviously to generate records and run the INSERT query against the different table.
Seems like I do something wrong, because no matter what I trying, I getting different errors here, like mysql.connector.errors.OperationalError: MySQL Connection not available..
(upd) I also tried to change the code like it was suggested (see example bellow), with no luck - I still receiving the MySQL connection not available. error.
rows = cursor.fetchall()
cursor.close()
for sensor in rows:
cursor2 = db.cursor()
generateRecords(sensor, cursor2)
So, should I create a new connection within generateRecords function, or pass something different within it, or use some kind of different approach here?
Thank you!
Finally I found what was wrong. I'm used the query to call the stored procedure. Using the cursor.callproc("sp_sensors_overview") instead fixed my issue, and now I'm able to create the next cursor without errors.
Usually I connect to a database in Pymongo like this:
# connect to the MongoDB
connection = MongoClient("mongodb://127.0.0.1:27017")
# connect to the database
self.db = self.connection.my_database
The problem is, the name of my_database always changes. How can I use a variable to choose the database?
Based on this documentation we can do it like this:
# connect to the MongoDB
connection = MongoClient("mongodb://127.0.0.1:27017")
# connect to the database
a = 'my_database'
self.db = self.connection[a]
Im able to connect to Oracle Db successfully when i hardcode the Db details like " connection = cx_Oracle.connect("uname/pass#192.168.xxx.yyy:port/db")" but how to pass the variable values to connect to the db?
I tried some like this.
connection = cx_Oracle.connect("{}/{}#{}:{}/{}".format(uname,password,IP,port,db))
which is not working as expected so please share some thought on this to make it work.
def knowcobrand(request):
value_type = request.POST.get('CobranSelection')
cobrand_value = request.POST.get('cobrand')
env = request.POST.get('NewEnvName')
print(value_type)
print(cobrand_value)
print(env)
# feed = Environments.objects.get(Q(Env_name__icontains=env))
# print(feed.user_name)
connection = cx_Oracle.connect("app/app#192.168.xxx.yy:port/db")
I want to use the variable's value of value_type and env for Db connection
EDIT: You should probably run through the Django tutorial, it will explain the basics of Django and using the ORM
You should configure your database connection in your settings
There is a specific example for oracle
You can now use the Django ORM (after running migrations)
If you want a raw cursor for the database you can still use Django for this like so
from django.db import connection
with connection.cursor() as c:
c.execute(...)
I have a program using Python + python mysql connector + Mysql which is installed in a network and uses the same database. How do I refresh a connection without restarting the program on other Machines?
The Program is installed in more than one Machine and connects to the same Mysql database which is located on a Server. The program is working properly, but,
when a new data is entered or modified "SQL INSERT, UPDATE.... Statments" from one machine is not reflected in all other Machines until the program is restarted, which means that a new connection is necessary to show the new database data.
So, I would like to know how to refresh the connection without restarting the program on other machines.
Here is the sample Connection code:
import mysql.connector as mc
conn = mc.connect(host='host', user='user', passwd='passw', db='db_name', port=port_number)
cur = conn.cursor()
How to refresh This Connection while the program is running?
closing and reopening connection may also solve your problem,
see following example in loop
import mysql.connector as mc
conn = mc.connect(host='host', user='user', passwd='passw', db='db_name', port=port_number)
while True:
# check if youre connected, if not, connect again
if (conn.is_connected() == False):
conn = mc.connect(host='host', user='user', passwd='passw', db='db_name', port=port_number)
cur = conn.cursor()
sql = "INSERT INTO db_name.myTable (name) VALUES (%(val)s);"
val = {'val':"Slim Shady"}
cur.execute(sql,val)
conn.commit()
conn.close()
After inserting or updating, you should do a commit to make sure all data it's writed to the DB. Then it will be visible for everyone:
conn.commit()