Query to find foreign keys

Question

I have a database where I need to drop some foreign keys, but I don\'t know beforehand whether the foreign keys still exist.

I\'ve found some stored procedures (http

Answer 1

You need to connect to the Information scheme and you can find all the information about the primary key and foreign keys in this table

 select
        concat(table_name, '.', column_name) as 'foreign key',  
        concat(referenced_table_name, '.', referenced_column_name) as 'references'
    from
        information_schema.key_column_usage
    where
        referenced_table_name is not null;

HELP: see this link list-foreign-keys-in-mysql

Answer 2

You need to connect to the Information scheme and you can find all the information about the primary key and foreign keys in this table

SELECT * FROM information_schema.TABLE_CONSTRAINTS T;

you need to be a ROOT user to access the information_schema.

USING this table you can find the table, db and whether it has foreign key.

Hope this helps if you dont wanna use IF EXIST and Stored Procedure. But I am Sure you can use IF EXIST can be used for non stored procedure queries....

Answer 3

Why don't You use the table "INFORMATION_SCHEMA" to this?

SELECT *
FROM information_schema.TABLE_CONSTRAINTS
WHERE CONSTRAINT_TYPE = 'FOREIGN KEY'