Rails table indexes are not foreign keys in database as expected - why?
134117
Defining foreign key relationships for Rails' models
158559
Why does Postgres generate an already used PK value?
149263
How do I find all tables in a DB that have no explicit primary key?
41165
Foreign key constraints failures
60528
What's wrong with foreign keys?
142083
Restored database missing views, stored procs and foreign keys
127553
Why is this MySQL SELECT performing so slowly despite indexing?
153310
Composite primary key from multiple tables / multiple foreign keys
8210
MySQL not using indexes with WHERE IN clause?
18217
Does Foreign Key improve query performance?
96901
How to list of all the tables defined for the database when using active record?
129426
Table doesn't have a primary key
80490
Does MySQL foreign_key_checks affect the entire database?
158985
Can a foreign key be NULL and/or duplicate?
17038
MySQL Creating tables with Foreign Keys giving errno: 150
47564
Foreign Key column mapped to multiple primary keys
112338
Why is PostgreSQL 9.5 not using my newest index for ORDER BY, even though it uses similar indices just fine?