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PostgreSQL Error while executing sql command in Python

i've been trying to get some data from my db by using below code, but the code is not working. is there any mistake that i made in the code, if so how can i fix it.
NOTE: i took the below code from just a script not a django or flesk web app.
def db():
conn = psycopg2.connect(
"dbname=mydb user=postgres password=****** host=*.*.*.*")
cur = conn.cursor()
cur.execute("""SELECT * FROM MddPublisher""")
query_results = cur.fetchall()
print(query_results)
db()
ERROR: psycopg2.errors.UndefinedTable: relation "mddpublisher" does not exist LINE 1: SELECT * FROM MddPublisher
additionally,i want to show below code to prove that connection is ok. the problem is that i can't receive data from my db whenever i try to execute select command through python.
def print_tables():
conn = psycopg2.connect(
"dbname=mydb user=postgres password=***** host=*.*.*.*.*")
cur = conn.cursor()
cur.execute("""SELECT table_name FROM information_schema.tables
WHERE table_schema = 'public'""")
for table in cur.fetchall():
print(table)
print_tables()
OUTPUT:
('MddPublisher',)

This is probably an issue with case sensitivity. Postgresql names are usually normalized to lower case. However, when used inside double quotes, they keep their case. So, to access a table named MddPublisher you must write it like "MddPublisher".
All the gory details are in Section 4.1.1, Identifiers and Key Words in the Postgresql 14 docs.

How to create a database with psycopg2 using execute() second argument?

I'm trying to create a database with the name a user will provide. As far as I know the correct way is to use the second argument of execute().
So I did as follows:
import psycopg2
conn = psycopg2.connect(host="...", dbname="...",
user="...", password="...", port='...')
cursor = conn.cursor()
query = ''' CREATE DATABASE %s ;'''
name = 'stackoverflow_example_db'
conn.autocommit = True
cursor.execute(query, (name,))
cursor.close()
conn.close()
And I got this error:
psycopg2.errors.SyntaxError: syntax error at or near "'stackoverflow_example_db'"
LINE 1: CREATE DATABASE 'stackoverflow_example_db' ;
I need to do this statement avoiding SQL injection, so using the second argument is a must.

You can't pass values as second argument of execute(), if the statement is a CREATE DATABASE one.
As pointed out by unutbu one way to approach this is using the psycopg2.sql submodule and use identifiers to build the statement avoiding SQL injection.
The code:
import psycopg2
from psycopg2 import sql
conn = psycopg2.connect(host="...", dbname="...",
user="...", password="...", port='...')
cursor = conn.cursor()
query = ''' CREATE DATABASE {} ;'''
name = 'stackoverflow_example_db'
conn.autocommit = True
cursor.execute(sql.SQL(query).format(
sql.Identifier(name)))
cursor.close()
conn.close()
Other aditional observations:
format() do not work with %s, use {} instead
Autocommit mode is a must for this statement to work
The specified connection user needs creation privileges

MySQL python connector code aborts without error (Code from the MySQL documentation)

I was trying to use the python connector code given in the MySQL documentation and test it on a small database already created, but it aborts. The code is just supposed to connect to the db and add a new email adress.
import mysql.connector
from mysql.connector import errorcode
cnx = mysql.connector.connect(user='root', password='pwd', host='localhost', database='db')
cursor = cnx.cursor()
add_email = ("INSERT INTO employee(MID, Email) VALUES (%s,%s)")
email_details = (NULL, "a#a.de")
cursor.execute(add_email, email_details)
cnx.commit()
input("data entered successfully")
cnx.close()
By setting breakpoints I found out that the problem probably lies in the cursor.execute() statement. (I used Null as the first %s since MID is Auto Incrementing btw)

To solve this problem NULL (for the autoincrementing "MID") needs to be replaced with None.

SQL Select where not working

I am using Python/Flask and trying to query my DB.
conn = sqlite3.connect('./flaskdb.db')
cur = conn.cursor()
cur.execute('SELECT email FROM users WHERE email=\'%s\'', "name")
I have 2 columns, email, password and the value name, password as one of the row/entries.
Why isn't this working? I get the error:
sqlite3.ProgrammingError: Incorrect number of bindings supplied. The current statement uses 0, and there are 7 supplied.

I think you are getting bogged down with using prepared statements here. Try this code:
conn = sqlite3.connect('./flaskdb.db')
cur = conn.cursor()
name = 'someone#somewhere.com'
cur.execute('SELECT email FROM users WHERE email=?', (name,))
Corrections include using ? as a placeholder instead of %s, the latter which is what might be used for other databases. Also, if you want to bind a variable called name, then it too should not have quotes around it.

I have a solution:
cur.execute('SELECT password FROM users WHERE email=(?)', (email,))
you need it as a tuple and (?) as a placeholder.

Empty table in MySQL even though Python can insert data into table

I'm new to mySQL and Python.
I have code to insert data from Python into mySQL,
conn = MySQLdb.connect(host="localhost", user="root", passwd="kokoblack", db="mydb")
for i in range(0,len(allnames)):
try:
query = "INSERT INTO resumes (applicant, jobtitle, lastworkdate, lastupdate, url) values ("
query = query + "'"+allnames[i]+"'," +"'"+alltitles[i]+"',"+ "'"+alldates[i]+"'," + "'"+allupdates[i]+"'," + "'"+alllinks[i]+"')"
x = conn.cursor()
x.execute(query)
row = x.fetchall()
except:
print "error"
It seems to be working fine, because "error" never appears. Instead, many rows of "1L" appear in my Python shell. However, when I go to MySQL, the "resumes" table in "mydb" remains completely empty.
I have no idea what could be wrong, could it be that I am not connected to MySQL's server properly when I'm viewing the table in MySQL? Help please.
(I only use import MySQLdb, is that enough?)

use commit to commit the changes that you have done
MySQLdb has autocommit off by default, which may be confusing at first
You could do commit like this
conn.commit()
or
conn.autocommit(True) Right after the connection is created with the DB