Develop Reference

psycopg2.errors.UndefinedTable: [duplicate]

I'm trying to figure out why I can't access a particular table in a PostgreSQL database using psycopg2. I am running PostgreSQL 11.5
If I do this, I can connect to the database in question and read all the tables in it:
import psycopg2
try:
connection = psycopg2.connect(user = "postgres", #psycopg2.connect() creates connection to PostgreSQL database instance
password = "battlebot",
host = "127.0.0.1",
port = "5432",
database = "BRE_2019")
cursor = connection.cursor() #creates a cursor object which allows us to execute PostgreSQL commands through python source
#Print PostgreSQL version
cursor.execute("""SELECT table_name FROM information_schema.tables
WHERE table_schema = 'public'""")
for table in cursor.fetchall():
print(table)
The results look like this :
('geography_columns',)
('geometry_columns',)
('spatial_ref_sys',)
('raster_columns',)
('raster_overviews',)
('nc_avery_parcels_poly',)
('Zone5e',)
('AllResidential2019',)
#....etc....
The table I am interested in is the last one, 'AllResidential2019'
So I try to connect to it and print the contents by doing the following:
try:
connection = psycopg2.connect(user = "postgres",
#psycopg2.connect() creates connection to PostgreSQL database instance
password = "battlebot",
host = "127.0.0.1",
port = "5432",
database = "BRE_2019")
cursor = connection.cursor() #creates a cursor object which allows us to execute PostgreSQL commands through python source
cursor.execute("SELECT * FROM AllResidential2019;") #Executes a database operation or query. Execute method takes SQL query as a parameter. Returns list of result
record = cursor.fetchall()
print(record)
except (Exception, psycopg2.Error) as error:
print("Error while connecting to PostgreSQL: ", error)
And I get the following error:
Error while connecting to PostgreSQL: relation "allresidential2019" does not exist
LINE 1: SELECT * FROM AllResidential2019;
However, I can successfully connect and get results when attempting to connect to another table in another database I have (this works! and the results are the data in this table):
try:
connection = psycopg2.connect(user = "postgres", #psycopg2.connect() creates connection to PostgreSQL database instance
password = "battlebot",
host = "127.0.0.1",
port = "5432",
database = "ClimbingWeatherApp") . #different database name
cursor = connection.cursor()
cursor.execute("SELECT * FROM climbing_area_info ;")
record = cursor.fetchall()
print(record)
except (Exception, psycopg2.Error) as error:
print("Error while connecting to PostgreSQL: ", error)
I can't figure out why I can retrieve information from one table but not another, using exactly the same code (except names are changes). And I am also not sure how to troubleshoot this. Can anyone offer suggestions?

Your table name is case-sensitive and you have to close it in double quotes:
SELECT * FROM "AllResidential2019";
In Python program it may look like this:
cursor.execute('SELECT * FROM "AllResidential2019"')
or you can use the specialized module SQL string composition:
from psycopg2 import sql
# ...
cursor.execute(sql.SQL("SELECT * FROM {}").format(sql.Identifier('AllResidential2019')))
Note that case-sensitive Postgres identifiers (i.e. names of a table, column, view, function, etc) unnecessarily complicate simple matters. I would advise you not to use them.

Likely, the reason for your issue is Postgres' quoting rules which adheres to the ANSI SQL standard regarding double quoting identifiers. In your table creation, you likely quoted the table:
CREATE TABLE "AllResidential2019" (
...
)
Due to case sensitivity of at least one capital letter, this requires you to always quote the table when referencing the table. Do remember: single and double quotes have different meanings in SQL as opposed to being mostly interchangeable in Python.
SELECT * FROM "AllResidential2019"
DELETE FROM "AllResidential2019" ...
ALTER TABLE "AllResidential2019" ...
It is often recommended, if your table, column, or other identifier does not contain special characters, spaces, or reserved words, to always use lower case or no quotes:
CREATE TABLE "allresidential2019" (
...
)
CREATE TABLE AllResidential2019 (
...
)
Doing so, any combination of capital letters will work
SELECT * FROM ALLRESIDENTIAL2019
SELECT * FROM aLlrEsIdEnTiAl2019
SELECT * FROM "allresidential2019"
See further readings on the subject:
Omitting the double quote to do query on PostgreSQL
PostgreSQL naming conventions
Postgres Docs - 4.1.1. Identifiers and Key Words
Don’t use double quotes in PostgreSQL
What is the difference between single and double quotes in SQL?

I was facing the same error in Ubuntu. But in my case, I accidentally added the tables to the wrong database, which was in turn owned by the root postgres user instead of the new postgres user that I had created for my flask app.
I'm using a SQL file to create and populate the tables. This is the command that I used to be able to create these tables using a .sql file. This allows you to specify the owner of the tables as well as the database in which they should be created:
sudo -u postgres psql -U my_user -d my_database -f file.sql -h localhost
You will then be prompted for my_users's password.
sudo -u postgres is only necessary if you are running this from a terminal as a the root user. It basically runs the psql ... command as the postgres user.

How to specify the specific database on the server in cx_oracle.connect

I have to connect to an Oracle server and only use a specific database on the server. I have logon information like this:
hostname = 'xxxxx.yyyy.xxxx.net:1521/{server_name}'
user_name= 'user'
password = 'password'
db_name= 'uuuu'
cx_Oracle.connect(user_name, password, hostname)
How can specify the db_name in the connect statement in the connect statement?
The above allows me to query: select * from uuuu.my_table;. So how can I specify uuuu in the connect such that I don't have to add each time.

"uuuu" in your example appears to be a schema name not a database name. You cannot specify a schema name in your connection string (other than by logging in as the "uuuu" user). Once you have connected to the database, however, you can run the statement
alter session set current_schema = uuuu;
That will cause the statement
select * from my_table
to look for a my_table object in the "uuuu" schema rather than looking for it in the current user's schema. Alternatively, you can create synonyms (public or private) for my_table and the other "uuuu" schema objects you want to reference.

From the docs...
import cx_Oracle
userpwd = ". . ." # Obtain password string from a user prompt or environment variable
connection = cx_Oracle.connect("hr", userpwd, "dbhost.example.com/orclpdb1", encoding="UTF-8")
The 'ocrlpdb1' at the end of the connect string, that's the Service name for the database, that is running on dbhost.example.com. We're assuming Oracle Listener on that machine is using port 1521 (the default).

Unknown Database Error python mysql

This link contains shows the database I've created in the mysql workbench and the connection I have established in the code but the database is unknown for some reason. Is there a step I've missed?
http://gyazo.com/d995c4da99043da43bfbd057a0a839c7
__author__ = 'avi'
from TwitterSearch import *
import json
twtsearch = TwitterSearch(
consumer_key='PXTUrlRfgC1zSTsAPU9z6EHtD',
consumer_secret='qM9F4FVj1qLFc6f795r96DQPNAJO8hkbWy4PXWYLfQcYyNGY7D',
access_token='2943116292-wVHEjbfjX7OFqaOURBqim5o7Vs6lZyjxsoto8nD',
access_token_secret='CJAppSRY9TZ5cwYTABZhH2YTd0rm5IzBDqPder6v4qLBA'
)
twtsearchorder = TwitterSearchOrder()
twtsearchorder.set_keywords(['iphone6'])
twtsearchorder.set_language('en')
twtsearchorder.set_include_entities(True)
tweet_limit=50
parsed_tweets= {}
table="twtinfo"
import MySQLdb as mdb
con = mdb.connect('localhost', 'root','root','tweetinfo')
cur=con.cursor()
for tweet in twtsearch.search_tweets_iterable(twtsearchorder):
if tweet_limit > 0 :
parsed_tweets['name'] = tweet['user']['screen_name']
parsed_tweets['content'] = tweet['text']
parsed_tweets['user_id'] = tweet['user']['id']
parsed_tweets['fav_count'] = tweet['favorite_count']
parsed_tweets['location'] = tweet['user']['location']
parsed_tweets['retweet_count'] = tweet['retweet_count']
placeholders= ', '.join(['%s'] *len(parsed_tweets))
columns = ', '.join(parsed_tweets.keys())
sql="INSERT into %s ( %s ) VALUES ( %s )" % (table, columns, placeholders)
cur.execute(sql,parsed_tweets.values())
tweet_limit -= 1

The MySQL process is complaining about the database you are trying to access, namely tweetinfo isn't existing. MySQL error 1049 is usually an indication of having to forgot to select a database, but you did as forth argument to mdb.connect()
Possible errors could be:
That you have several MySQL processes running, with the one with the proper database not being on the default MySQL port.
That somehow your database GUI application hasn't actually submitted your database and table to the MySQL process.
That MySQL isn't running? You would probably get a different error message for that, but it could be an idea to make sure it is just in case.
Just to check if your tables exists and that your database is in place, open a terminal and write the following commands:
mysql -u root -proot
use tweetinfo;
show create table twtinfo;
Another thing to try could be to ask the MySQL process about which database it thinks you are using. Try adding something like the following to your code:
cur.execute("SELECT DATABASE() FROM DUAL;")
print("Database is: %s.", cur.fetchone()[0])
I'm not a python programmer, so I'm not entirely confident that will work without some adjustments.
If none of this gave you a good lead, I'm not quite sure what's wrong.

How to import sql via shell in Python?

I have case :
import pymysql
conn = pymysql.connect(host='127.0.0.1', unix_socket='/opt/lampp/var/mysql/mysql.sock', user='root', passwd=None, db='test')
cur = conn.cursor()
cur.execute("test < /mypath/test.sql")
cur.close()
conn.close()
I always get error :
1064 , "You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'test < /mypath/test.sql' at line 1"
I tried to use source and it still failed. Did you know why?
Thank you.

Your error message says that the MySQL server can't understand
test < /mypath/test.sql' at line 1
If you're a long time *nix user, it seems intuitive that you should be able to use commands like this to pass various sorts of data streams to various programs. But that's not the way the Python sql API (or most language-specific) sql APIs works.
You need to pass a valid SQL query to the execute() method in the API, so the API can pass it to the database server. A vaild query will be something like INSERT or CREATE TABLE.
Look, the server might be on a different host machine, so telling the server to read from /mypath/test.sql is very likely a meaningless instruction to that server. Even if it did understand it, it might say File test.sql not found.
The mysql(1) command line client software package can read commands from files. Is that what you want?

>>> import MySQLdb
>>> db = MySQLdb.connect(host = 'demodb', user = 'root', passwd = 'root', db = 'mydb')
>>> cur = db.cursor()
>>> cur.execute('select * from mytable')
>>> rows = cur.fetchall()
Install MySQL-Python package to use MySQLdb.

MySQLdb: how to connect with phpMyAdmin

I have a LAMP server and then I installed MySQLdb for my Python scripts. Now I can't access the MySQL (from LAMP) from Python scripts because it isn't connecting to the MySQLdb, and also I can't access the MySQLdb with phpMyAdmin with (root root). I got "#2002 Cannot log in to the MySQL server" error. Is it possible to connect to one db with Python and phpMyAdmin?
Here is my Python code, which can't connect to the LAMP MySQL, but can connect to the MySQLdb:
db = MySQLdb.connect(host="localhost", port=3303, user="root", passwd="rootroot", db="test")
cursor = db.cursor()
sql = "CREATE TABLE TT(ID int NOT NULL AUTO_INCREMENT PRIMARY KEY)"
cursor.execute(sql)
db.commit()
db.close()

If you're getting #2002 Cannot log in to the MySQL server when logging in to phpmyadmin, then edit phpmyadmin/config.inc.php file and change:
$cfg['Servers'][$i]['host'] = 'localhost';
to:
$cfg['Servers'][$i]['host'] = '127.0.0.1';
You might want to visit this link:
http://blog.ryantremaine.com/2011/03/2002-cannot-log-in-to-mysql-server.html
UPDATE:
you wud not have configured your php.ini well and so that it cannot connect to mysql server.
Wrong path for the mysql.sock
mysql.sock is the instance of the mysql, so first you have to find where does it place at.
You may find it at "/tmp/mysql.sock" or "/var/mysql/mysql.sock".
Go to your php.ini and make sure the value for "pdo_mysql.default_socket", "mysql.default_socket", "mysqli.default_socket" is the right path.
Then restart your web server and try again.
ELSE
Try this:
Go to config.inc.php and check for the following line:
$cfg['Servers'][$i]['user'] = 'YOUR USER NAME IS HERE';
$cfg['Servers'][$i]['password'] = 'AND YOU PASSWORD IS HERE';
Check whether the user name and password that you gave is present or not