What is a foreign key? It’s a column that must match a key in another table, and SQL Server refuses any value that has no match. This post shows the error it raises, the ON DELETE options, and why the foreign key column needs an index of its own.
Adding a NOT NULL Column With a Default to a Big Table
Add a NOT NULL column with a default safely, distinguish metadata changes from row updates, and plan a staged Standard edition rollout.
SQL SERVER – Disable All the Foreign Key Constraint in Database – Enable All the Foreign Key Constraint in Database
A tester wanted to load bad data, but foreign keys got in the way. Here is how to disable all the foreign key constraints in a database and enable them again.
SQL SERVER – Fix: Error: 1505 The CREATE UNIQUE INDEX statement terminated because a duplicate key was found for the object name and the index name
Error 1505 says the CREATE UNIQUE INDEX statement terminated because a duplicate key was found. The word key confuses many developers, so I explain it simply.
Walking Foreign Key Chains to Find a Safe Delete Order
Map foreign key chains from a parent table with a recursive catalog query, then list deepest children first and flag cascade rules.
Audit Columns From Day One: CreatedAt, UpdatedAt and Who Changed It
Add audit columns with UTC timestamps and trusted change identities, maintain updates in procedures, and know when history is needed.
A Multi-Tenant Schema With a TenantId Column: Keys, Indexes and Safety
Design a multi-tenant schema with composite keys, tenant-first indexes, trusted session context, and row-level security checks.