[mysql] MySQL Cannot Add Foreign Key Constraint

Confirm that the character encoding and collation for the two tables is the same.

In my own case, one of the tables was using utf8 and the other was using latin1.

I had another case where the encoding was the same but the collation different. One utf8_general_ci the other utf8_unicode_ci

You can run this command to set the encoding and collation for a table.

ALTER TABLE tablename CONVERT TO CHARACTER SET utf8 COLLATE utf8_unicode_ci;

I hope this helps someone.

Examples related to mysql

Implement specialization in ER diagram How to post query parameters with Axios? PHP with MySQL 8.0+ error: The server requested authentication method unknown to the client Loading class `com.mysql.jdbc.Driver'. This is deprecated. The new driver class is `com.mysql.cj.jdbc.Driver' phpMyAdmin - Error > Incorrect format parameter? Authentication plugin 'caching_sha2_password' is not supported How to resolve Unable to load authentication plugin 'caching_sha2_password' issue Connection Java-MySql : Public Key Retrieval is not allowed How to grant all privileges to root user in MySQL 8.0 MySQL 8.0 - Client does not support authentication protocol requested by server; consider upgrading MySQL client

Examples related to sql

Passing multiple values for same variable in stored procedure SQL permissions for roles Generic XSLT Search and Replace template Access And/Or exclusions Pyspark: Filter dataframe based on multiple conditions Subtracting 1 day from a timestamp date PYODBC--Data source name not found and no default driver specified select rows in sql with latest date for each ID repeated multiple times ALTER TABLE DROP COLUMN failed because one or more objects access this column Create Local SQL Server database

Examples related to foreign-keys

Migration: Cannot add foreign key constraint The ALTER TABLE statement conflicted with the FOREIGN KEY constraint Can a foreign key refer to a primary key in the same table? Introducing FOREIGN KEY constraint may cause cycles or multiple cascade paths - why? MySQL Error 1215: Cannot add foreign key constraint MySQL Cannot Add Foreign Key Constraint Delete rows with foreign key in PostgreSQL How to remove constraints from my MySQL table? MySQL - Cannot add or update a child row: a foreign key constraint fails How to remove foreign key constraint in sql server?