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10.12.2 errors.Error Exception

This exception is the base class for all other exceptions in the errors module. It can be used to catch all errors in a single except statement.

The following example shows how we could catch syntax errors:

import mysql.connector

  cnx = mysql.connector.connect(user='scott', database='employees')
  cursor = cnx.cursor()
  cursor.execute("SELECT * FORM employees")   # Syntax error in query
except mysql.connector.Error as err:
  print("Something went wrong: {}".format(err))

Initializing the exception supports a few optional arguments, namely msg, errno, values and sqlstate. All of them are optional and default to None. errors.Error is internally used by Connector/Python to raise MySQL client and server errors and should not be used by your application to raise exceptions.

The following examples show the result when using no arguments or a combination of the arguments:

>>> from mysql.connector.errors import Error
>>> str(Error())
'Unknown error'

>>> str(Error("Oops! There was an error."))
'Oops! There was an error.'

>>> str(Error(errno=2006))
'2006: MySQL server has gone away'

>>> str(Error(errno=2002, values=('/tmp/mysql.sock', 2)))
"2002: Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2)"

>>> str(Error(errno=1146, sqlstate='42S02', msg="Table 'test.spam' doesn't exist"))
"1146 (42S02): Table 'test.spam' doesn't exist"

The example which uses error number 1146 is used when Connector/Python receives an error packet from the MySQL Server. The information is parsed and passed to the Error exception as shown.

Each exception subclassing from Error can be initialized using the previously mentioned arguments. Additionally, each instance has the attributes errno, msg and sqlstate which can be used in your code.

The following example shows how to handle errors when dropping a table which does not exist (when the DROP TABLE statement does not include a IF EXISTS clause):

import mysql.connector
from mysql.connector import errorcode

cnx = mysql.connector.connect(user='scott', database='test')
cursor = cnx.cursor()
  cursor.execute("DROP TABLE spam")
except mysql.connector.Error as err:
  if err.errno == errorcode.ER_BAD_TABLE_ERROR:
    print("Creating table spam")

Prior to Connector/Python 1.1.1, the original message passed to errors.Error() is not saved in such a way that it could be retrieved. Instead, the Error.msg attribute was formatted with the error number and SQLSTATE value. As of 1.1.1, only the original message is saved in the Error.msg attribute. The formatted value together with the error number and SQLSTATE value can be obtained by printing or getting the string representation of the error object. Example:

  conn = mysql.connector.connect(database = "baddb")
except mysql.connector.Error as e:
  print "Error code:", e.errno        # error number
  print "SQLSTATE value:", e.sqlstate # SQLSTATE value
  print "Error message:", e.msg       # error message
  print "Error:", e                   # errno, sqlstate, msg values
  s = str(e)
  print "Error:", s                   # errno, sqlstate, msg values

errors.Error is a subclass of the Python StandardError.