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.

python mysql connector, how to create user defined database

how do I create a database or table using python mysql connector where the name of the database/table has to be taken as a input from the user. I tried the following but it doesn't works:
mycursor.execute("create database %s", (database_name))

you should make connection without db name.
This should work
conn = pymysql.connect('localhost','user','password')
cur = conn.cursor(pymysql.cursors.DictCursor)
cur.execute('CREATE DATABASE %s;'%('DB_NAME_TO_MAKE'))

MySQL not responding after I execute SELECT statement

I have a Python code where I am having database statements to establish a database connection and insertion statement. Below is the code which I have written. The program is running correctly but when I open MySQL and run SELECT statement, there is no response from database. It's stuck for a long time.
import MySQLdb
dsn_database = "project"
dsn_hostname = "localhost"
dsn_port = 3306
dsn_uid = "root"
dsn_pwd = "pwd"
conn = MySQLdb.connect(host=dsn_hostname, port=dsn_port, user=dsn_uid, passwd=dsn_pwd, db=dsn_database)
conn.query("""DROP TABLE IF EXISTS cars""")
conn.query("""CREATE TABLE cars(Id INTEGER PRIMARY KEY, Name VARCHAR(20), Price INT)""")
conn.query("""INSERT INTO cars VALUES(1,'Audi',52642)""")

MySQL Connector/Python stored procedure insert not committing

I'm writing a python script to monitor a few 1wire sensors off of a Raspberry Pi and store the results in a MySQL database.
Using the MySQL Connector/Python library I can successfully connect to the database, and run the query however the transaction doesn't seem to fully commit. I know the query runs successfully since the out param is set to the new auto-incremented ID.
CREATE TABLE `lamp`.`sensors` (
`SensorID` int(11) unsigned NOT NULL AUTO_INCREMENT,
`SensorSerial` char(15) NOT NULL,
`SensorFamily` tinyint(4) NOT NULL,
PRIMARY KEY (`SensorID`),
UNIQUE KEY `SensorID_UNIQUE` (`SensorID`),
UNIQUE KEY `SensorSerial_UNIQUE` (`SensorSerial`)
)
CREATE PROCEDURE `lamp`.`AddSensor` (sensorSerial char(15),
sensorFamily tinyint, out returnValue int)
BEGIN
INSERT INTO sensors (SensorSerial,SensorFamily) VALUES (sensorSerial,sensorFamily);
SET returnValue=LAST_INSERT_ID();
END
However when I attempt to query the table (Select * from sensors) I get 0 results. If I run the procedure from the MySQL Workbench or from a .Net application everything works as expected. Which means I'm missing something when it comes to the Connector/Python, but I have no clue what. I'm extremely baffled since the auto-increment value does increase but no records are added. There are also no errors reported
def Test(self):
#this line works fine
#self.RunProcedure("INSERT INTO sensors (SensorSerial,SensorFamily) VALUES ('{0}',{1})".format(self.ID,self.Family),False,())
#this line does not?
args=self.RunProcedure('AddSensor',True,(self.ID,self.Family,-1))
if args[2]>=1:
logging.debug("Successfully added sensor data '{1}' for sensor '{0}' to the database".format(self.ID,value))
return True
else:
logging.critical("Failed to add Data to Database for unknown reason. SensorID: {0} Type: {1} Data:{2}".format(self.ID,self.Family,value))
def RunProcedure(self,proc,isStored,args):
try:
logging.debug("Attempting to connect to database.")
connection=mysql.connector.connect(user='root',password='1q2w3e4r',host='localhost',database='LAMP')
except mysql.connector.Error as e:
logging.exception("Failed to connect to mysql database.\r\n {0}".format(e))
else:
logging.debug("Successfully connected to database.")
try:
cursor=connection.cursor()
if isStored:
args = cursor.callproc(proc,args)
return args
else:
cursor.execute(proc,args)
#these do not seem to solve the issue.
#cursor.execute("Commit;")
#connection.commit()
except mysql.connector.Error as e:
logging.exception("Exception while running the command '{0}' with the args of '{1}' exception is {2}".format(proc,args,e))
finally:
logging.debug("Closing connection to database")
cursor.close()
connection.close()
Output from to the log looks like this;
2013-06-09 13:21:25,662 Attempting to connect to database.
2013-06-09 13:21:25,704 Successfully connected to database.
2013-06-09 13:21:25,720 Closing connection to database
2013-06-09 13:21:25,723 Successfully added sensor data '22.25' for sensor '10.85FDA8020800' to the database
**Edit
Not sure why but adding autocommit=True to the connection.open params seems to have resolved the issue. Since it was a problem with committing why didn't connection.commit() or the cursor.execute('commit;') correct the issue?

The problem is actually in your code:
..
try:
cursor=connection.cursor()
if isStored:
args = cursor.callproc(proc,args)
return args
else:
cursor.execute(proc,args)
connection.commit()
except mysql.connector.Error as e:
..
If you are using the Stored Routine, you are immediately returning, so commit() will never be called.

sqlite + python: cannot update record

I use sqlite3 with python. I can CRUD tables via command line.
I can also successfully select, insert and delete (!) records via python. However, when I (within the very same connection context) try to update I get the exception: "unable to open database file".
I am puzzled, any ideas?
PS: The tables were created via Django's manage.py syncdb if this is of any relevance.
PPS: I am running the code through CGI (granted all permissions to the file, that's why I can also add to the database)
Sorry missed the code:
sDb = 'this\is\my\db'
conn = sqlite3.connect( sDb )
cursor = conn.cursor()
# below works:
sSql = "insert into app_filestamp ( file_id, sFileStamp ) values ( 12, 'YYYYY' )"
# below raises the error
sSql = "update app_filestamp set sFileStamp='XXXXX' where id=13"
cursor.execute( sSql )
conn.commit()
conn.close()
"Solution"
This awkward behaviour (insert works, update not) did only happened on a Windows environment.
Thanks for all your input; since this is obviously no known issue I re-thought my approach and got rid of the need for CGI.
Bear with me that I did not further investigate the issue.