Question

I know how to detect the foreign tables, foreign fields, references. But I dont know what to do, CASCADE or SET TO NULL. Describe table wont return this information, neither information_schema. Then how?

Answer 1

You should be able to use the SHOW CREATE TABLE command to see everything (all fields, their types, foreign keys, etc.)

If you are using the data programmatically, then you can query it from the INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS table using the UPDATE_RULE and DELETE_RULE columns