python to mysql insert error

Question

I'm trying to insert data into a database hosted on Network Solutions using python and the code below. I was able to successfully connect to the db but when I tried to insert the data into the table I get this error:

1452 (23000): Cannot add or update a child row: a foreign key constraint fails (`focused`.`test_results`, CONSTRAINT `test_results_practice_tests_FK` FOREIGN KEY (`practice_test_id1`) REFERENCES `practice_tests` (`practice_test_id`))

import mysql.connector
from mysql.connector import errorcode

config = {
  'user': '{user}',
  'password': '{psswd}',
  'host': '{host}',
  'database': '{dbname}',
  'raise_on_warnings': True,
}

try:
  cnx = mysql.connector.connect(**config)
  cursor = cnx.cursor()

  query = """INSERT INTO test_results (result_id, student_id1, practice_test_id1, section_1_score, section_1_missed, section_2_score, section_2_missed, section_3_score, section_3_missed, section_4_score, section_4_missed, e_reading_score, e_analysis_score, e_writing_score, command_score, command_missed, words_score, words_missed, expression_score, expression_missed, heart_score, heart_missed, standard_score, standard_missed, problem_score, problem_missed, passport_score, passport_missed, history_score, history_missed, science_score, science_missed, math_score, reading_score) VALUES (%s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s)"""
  data_test_result = (1, 1, 1, 1, '', 1, '', 1, '', 1, '', 1, 1, 1, 1, '', 1, '', 1, '', 1, '', 1, '', 1, '', 1, '', 1, '', 1, '', 1, 1)
  cursor.execute(query, data_test_result)


except mysql.connector.Error as err:
  if err.errno == errorcode.ER_ACCESS_DENIED_ERROR:
    print("Something is wrong with your user name or password")
  elif err.errno == errorcode.ER_BAD_DB_ERROR:
    print("Database does not exist")
  else:
    print(err)
else:
  cnx.close()

This is a picture of the table structure for reference.

I was wondering what I can do to solve this problem and successfully insert the data into the table. Thanks so much for your help in advance!

Answer 1

The meaning of the error message is that the database structure defines a relationship between the table into which you are inserting data and another table called practice_tests . Values in your practise_test_id1 column are therefore required to exist as primary key values in the practice_tests table to maintain the "relational integrity" of the structure.

You should find that if you insert an appropriate row into practice_tests your code will work - but don't forget to call the connection's commit method otherwise your changes won't be made permanent.