General Error 1215 Cannot Add Foreign Key Constraint Laravel

It seems these both table are correct but when you run php artisan migrate. This is coming late, what I did was just to change the date of when any migration that has foreign key included in it to a later time beyond the table it has referenced. Laravel's "php artisan migrate" creates migration with respect to the date as found in the filename. This, however, could have been fixed by just creating a new migration file and making your edition in that new file. BigIncrements and unsignedBigInterger / smallIncrement vs unsignedSmallInteger for the corresponding table argument in here also help in resolving my problem.

For me the problem was not adding unsigned() on the user_id column so that it matched the data type of the id column on the users table. Laravel's increments('id') function creates an unsigned integer, so the foreign key column also needs to be unsigned. This will not affect any existing code in your project; however, be aware that foreign key columns must be of the same type.

Therefore, a column created using the increments method can not reference a column created using the bigIncrements method. Before renaming a table, you should verify that any foreign key constraints on the table have an explicit name in your migration files instead of letting Laravel assign a convention based name. Otherwise, the foreign key constraint name will refer to the old table name.

The table method on the Schema facade may be used to update existing tables. You can create a foreign key category_id in the posts table. Before creating the table structure for the posts table you have to create table structure of the categories table in Laravel. You have to create a migration file for the categories table and the migration file should be before the posts table migration file in the database/migrations directory.

Old org mirgation with newer account migration. Org table doesn't exist and the column types in org table is bigIncrement and the accounts foreign key is unsignedBigInteger but im getting the same error as OP for unable to add constraint. So I have this assignment which mandates us to follow the given attribute and table names. Unfortunately, one of the table names is a reserved keyword- 'Session'. Can you tell me how I should write the name of the session table so that phpmyadmin recognizes it as a table and not a keyword.

You don't need to set the table to Innodb, I am assuming laravel is now doing that. The migrations simply need to be timed correctly, which means you will modify the date code up in the filename for tables that you need foreign keys on. Alternatively or in addition, Lower the datecode for tables that don't need foreign keys.

The data type must be same for both the foreign key and referenced key. The size and sign of integer types must be the same. For character strings the character set and collation must be the same.

But, while we are creating databases through laravel using migration, an unsigned attribute is added with primary key, this was the place where i was stuck. So in order for foreign key to be created, it should also be unsigned. Check if your foreign key columns are the same type in related tables. For example - if ID in "notas" is unsignedBigInteger you won't be able to add it as FK in your current migration etc.

In my case the problem was with migration timing be care full while creating migrations firstly create the child migration than the base migration. Because if you create base migration first which have your foreign key will look for child table and there wont be table which than throw an exception. Because they new version of Laravel using by default use BIGINT for the primary key"id", then to resolve the problem of foreign key you need to create the same type in the child table. In my case the problem was with migration timing be careful while creating migrations firstly create the child migration than the base migration. Because if you create base migration first which have your foreign key will look for child table and there wont be table which then throw an exception. Also, this error can happen, if the referenced table is not created yet.

So, if the users table in this example is not exist in the database. We cannot add relations, unless related tables gets created. Lareavel run migrations order by date of migration files.

So if you wanna create a relation with a table that exists in 2nd migration file it fails. Suppose your comment table was created before your post table. Create your post table in a new migration file, then adding the foreign keys of the comment table in a new migration file you create after the post table migration have been created. Alternatively or in addition, Lower the datecode for tables that don't need foreign keys. Laravel run migrations order by date of migration files. So if you want to create a relation with a table that exists in 2nd migration file it fails.

Any ideas as to what I've done wrong, I want to get this right now, as I've got a lot of tables I need to create e.g. Users, Clients, Projects, Tasks, Statuses, Priorities, Types, Teams. Ideally I want to create tables which hold this data with the foreign keys, i..e clients_project and project_tasks etc. If the data type of primary key is an integer int then data type of foreign key should also be int.

It doesnot matter if the size are same or not. But data type must be same otherwise it will throw the same error. Create parent table first - Create the parent table . Like you have created the products table with a foreign key but you did not have created the discounts table then It will also give errors while migration. Migration files order issue - Migration files with foreign keys should be at the bottom in the migration folder or after the parent table .

Like if you have discount_id in the products table then the discounts table should be at the top or before the products table. You can also change the file name to solve the order issue. Usually it's bigInt vs int for me, but I just had a situation where I was trying to add foreign keys to tables that didn't exist yet, so changing the order that the migrations run fixed it. Any ideas as to what I've done wrong, I want to get this right now, as I've got a lot of tables I need to create e.g. While working on migration files in Laravel, it's relatively easy to forget one small detail which will restrict you from creating foreign keys.

# Modify the order in which the tables are created when performing database migration. Laravel is sorted by the date on the migration file name. 'Cannot add foreign key constraint'' is a common MySQL error.

This guide shows 12 ways you can dive into the error to find the root cause and. We are not using InnoDB as the engine on all tables.We are trying to reference a nonexistent key on the target table. Make sure it is a key on the other table The types of the columns are not the same . If you are using MySQL, you must use unsignedBigInteger on your foreign key. This is because bigIncrements are created as unsigned big integer under the hood, and we need to match the column types. I changed the parent table id's data type from BigIncrements to increments.

Schema Builder - Laravel, Today I was trying out Laravel's Migration. I tried to create two tables with the second table having a foreign key that reference the first table. A protip by ravinsharma7 about laravel, migration, and foreign key. I found that the primary keys were created using attribute "UNSIGNED" while the foreign key fields did not have that attribute.

I change the foreign key fields to "UNSIGNED" and bingo! It helped tremendously in diving into the details and there it was, as simple as that. So before I create the new table 'pages' which reference to the existing table 'categories' with a foreign key, I inserted a line to convert the table to InnoDB type. Dependent foreign key constraint violation in a referential integrity constraint. One thing that I think is missing from the answers on here, and please correct me if I am wrong, but the foreign keys need to be indexed on the pivot table. At least in mysql that seems to be the case.

Adding to the unsigned() solution, when creating database using InnoDB as the engine of the tables. Ensure that the foreign table was created before the tables that will depend on the foreign table. Then it will migrate the table and set the proper foreign keys without any issues. I hope you got the general idea in this post what are the possible reasons when migration fails. So, you have an existing project where you have already created all the migration ? As of Laravel 5.8, migration stubs use the bigIncrements method on ID columns by default.

Previously, ID columns were created using the increments method. So if you need to enforce foreign key reference checks, you should use InnoDB as your engine. One thing i have noticed is that if the tables use different engine than the foreign key constraint does not work.

Which is standard in most migrations, this will set up an unsigned integer field. This is happening because the user migration is run before creating the manager's table. So Change the migration with the following content will help you to create the foreign key under the manager table. That is, a column of the type "big integer" will be created as the primary key. You are getting this error because the foreign key constraint already exists. Try deleting the foreign key constraint on the owning side of things.

"Cannot insert explicit value for identity column in table '' when. I think don't works more to create foreignkey with /Integer but i'm not sure. However I do have hundreds of tables, so at the very end I have one last table for just foreign keys.

I am assuming I will pull those into the correct file and modify the datecode as i test them. In following laracasts, and in reading these posts, I believe the correct answer is similar to Vickies answer, with the exception that you don't need to add a separate schema call. You don't need to set the table to Innodb, I am assuming laravel is now doing that.

In my case I just change the order migrations are executed manually so table users is created first. The order of the migration file is important. The categories table must be created BEFORE the videos table.

The problem is because my 'categories' table was created as MyISAM type, which doesn't support foreign key. The problem was there was another table in the database that had a foreign key to the table I had deleted and was reloading. Make sure our parent table contains at least one key to which we are going to create a reference key.

Such an error occurs when the field referenced by the key has a different type, for example, unsigned is not there. On my case, I created migration file for comments first. After I changed the order, everything works fine. I just renamed the filed by interchanging the number in it. Also note that the type of user_id is set to unsigned to match the foreign key.

So far my code is working by adjusting the time code up to push back migrations that need foreign keys. MyISAM does not support foreign key constraints. It likely worked because switching to MyISAM caused it to completely ignore the foreign key which was probably there for a reason. I had this issue with laravel 5.8 and i fixed this code, as shown here in Laravel documentation, to where ever i am adding a foreign key.

As a notice be sure to use increments() over integer for the id , when u reference users .. I see users table done by Laravel 8 is not increments ... I am creating two tables, with 'one to many relationship.' Table 'users', and 'managers', where each user will have one manager, and each manager will have more than one user. My idea is to use 'id_stays_abroad' and 'user_id' as foreign keys. But MySQL never tells you exactly WHY it failed. There's actually a multitude of reasons this can happen.

This blog post is a compendium of the most common reasons why you can get ERROR 1215, how to diagnose your case to find which one is affecting you and potential solutions for adding the foreign key. To make the interface, the Foreign primary key and key types must be the same. Cannot an FK reference a PK of another type . You want to make a foreign key to a table which is not yet exists.

Make sure when we specify SET NULL action, define the columns in the child table as NOT NULL. Note that, in the above example, the data type of the id in student table is TINYINT but the data type of the student_id column in book table which referencing the student table. Only MySQL storage engine InnoDB supports foreign key, make sure we are using InnoDB storage engine. We can use the following command to determine which storage engine our server supports. These are the possible reasons i encountered when setting up foreign key and creating an migration hope it helps you as well. Categories migration should be created first before the products similarly user type should be created before the users migration so that migration will be created in an order without any problem.