What I want to do is put a Foreign Key from users_table column id into users_order table in the column user_id but when I try to do it says this. what did I do wrong or is there any other way to add foreign key to table in PhpMyAdmin ?
#1452 - Cannot add or update a child row: a foreign key constraint fails (`users`.`#sql-4830_792`, CONSTRAINT `#sql-4830_792_ibfk_1` FOREIGN KEY (`id`) REFERENCES `user_order` (`user_id`))
According to the docs,
For storage engines supporting foreign keys, MySQL rejects any INSERT or UPDATE operation that attempts to create a foreign key value in a child table if there is no a matching candidate key value in the parent table.
The error you see indicates that you are trying to add a new row to a child table, for which mo matching row is present in your parent table. To fix it, you can either add the row in your parent table before inserting a row in your child table, or remove NOT NULL constraints (if any) and insert a NULL value in the corresponding column. Once you do it, you will be able to add the foreign key constraint.
indexon 'user_id' column of 'user_order' table? – Himanshu Upadhyay