How can I list all foreign keys referencing a given table in mysql?
To see foreign key relationships of a table: SELECT TABLE_NAME, COLUMN_NAME, CONSTRAINT_NAME, REFERENCED_TABLE_NAME, REFERENCED_COLUMN_NAME FROM INFORMATION_SCHEMA. KEY_COLUMN_USAGE WHERE REFERENCED_TABLE_SCHEMA = ‘db_name’ AND REFERENCED_TABLE_NAME = ‘table_name’;
Can a primary key be a foreign key in the same table?
If you mean “can foreign key ‘refer’ to a primary key in the same table?”, the answer is a firm yes as some replied.
How to get list of foreign keys in SQL Server?
Below are two methods you can use to return a list of foreign keys for a given table in SQL Server. This is similar to returning the foreign keys based on the referenced/primary key table, except here, I’m returning the foreign keys based on the referencing/foreign key table itself.
How to avoid create table with foreign key reference?
If you’d like to make sure that the SQL engine won’t insert a row with a foreign key that references a non-existent primary key, then you can add a FOREIGN KEY constraint in your CREATE TABLE statement. You can see the error that it results in by removing the comments from the fourth INSERT in the code below.
How to travel the hierarchy of foreign keys?
This will travel the hierarchy of foreign keys for a given table and column and return columns from child and grandchild, and all descendant tables. It uses sub-queries to add r_table_name and r_column_name to user_constraints, and then uses them to connect rows. Here is an another solution.
How to select a subset of all foreign key constraints?
To select a subset of all foreign key constraints for a particular referenced table, all you need to do is add a WHERE clause designating the referenced table name. With just the default NO ACTION setting, there is mutual constraining between referenced and referencing tables in a foreign key relationship.