MSSQLMSSQL 547

MSSQL 547: Foreign Key Constraint Conflict

SQL Server error 547 is raised when an INSERT, UPDATE, or DELETE violates a foreign key constraint. The error message names the conflicting constraint and table.

Example Query

DELETE FROM customers WHERE customer_id = 1;
-- Fails if orders table has rows referencing customer_id 1

Common Causes

  1. 1Deleting a parent row that has dependent child rows
  2. 2Inserting a child row with a foreign key value not present in the parent
  3. 3Updating a primary key value that is referenced by child rows

How to Fix It

Delete or reassign child rows before deleting the parent. Add ON DELETE CASCADE to the constraint definition if automatic cleanup is desired. Use sp_fkeys 'table_name' to discover all foreign key relationships.

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