When executing a SQL query, I suddenly reported 1452, which made me totally confused.
In fact, the main reason for the error of 1452 is that there is no data in the main table corresponding to the child table with foreign keys.
For example:
Class list:
The

id	name
1	advanced classes
2	regular class Student table: id name class_id 1 * * 1 2 and 2 3 fifty 3 As a result, there is no data for the class with class_ID 3 for king 5 in the table. So no matter how you do the update statement on king five he’s going to report an error.   The real reason:   I copied a “class list” from the official library, and then I copied a “student list”, and then I made a mistake in the operation of the student list. Because after the class table was copied and before the student table was copied, new classes and students were added on the line. Then the data I copied here was only students, and no class was finished… It’s embarrassing. So don’t mess around…   Solution 1: Clear both tables and redo them. Solution 2: Use SQL to delete data that has no data in the main table corresponding to the foreign key. Take the above example: Delete Wang Wu. Read More: MySQL failed to add foreign key: SQL 1452 cannot add or update a child row:a foreign key constraint fails Mysql error 1452 – Cannot add or update a child row: a foreign key constraint fails MYSQL ERROR 1217 (23000): Cannot delete or update a parent row: a foreign key constraint fails Mysql error when deleting the table structure: Error Code: 1217. Cannot delete or update a parent row: a foreign key constraint fails MySQL error code 1217 (ER_ROW_IS_REFERENCED): Cannot delete or update a parent row: a foreign key co MySql ERROR CODE：1215 Cannot add the foreign key constraint Failed to add the foreign key constraint. Missing index for constraint ‘stu_ibfk_1’ in the reference 1822 – Failed to add the foreign key constraint. Missing index for constraint ‘tb_emp_ibfk_1’ in the MySQL failed to add foreign key error 1452 Ora-02292: integrity constraint (XX) violated – child record found foreign key Association, record cannot be deleted MySQL error 1451 23000 foreign key exception handling MySQL:Foreign key fails with error Error Code: 1452. The solution of duplicate entry ‘for key’ primary ‘when inserting data in MySQL Solution of duplicate entry ‘value’ for key ‘field name’ in MySQL Matlab delete row or col to delete the row or column of the matrix Global lock, table lock and row lock in MySQL mysql5.7.26：[ERR] 1118 – Row size too large (＞ 8126) About MySQL error: subquery returns more than 1 row mysql Error Code: 1022. Can’t write; duplicate key in table `xxx` About node error NPM update check failed try running with sudo or get access to the local update