Safely dropping a foreign-key column Before you drop a column that serves as a foreign key in a relational table, what must you do first?

Introduction / Context:
Foreign keys enforce referential integrity between a child table and a parent table. DDL operations that remove or alter the foreign-key column must respect these constraints to keep the catalog in a consistent state.

Given Data / Assumptions:

• A column participates in a FOREIGN KEY constraint referencing a parent table.
• We intend to drop that column from the child table.
• We have privileges to alter tables and constraints.

Concept / Approach:

Because the column is referenced by a constraint, the DBMS will block dropping it until the constraint is removed or altered. The correct sequence is to drop (or disable, depending on the DBMS) the foreign key constraint first, then drop the column. Dropping the primary key or the entire table is unnecessary and destructive relative to the stated goal.

Step-by-Step Solution:

Verification / Alternative check:

DBMS documentation universally prevents dropping a constrained column without first removing the dependent constraint, confirming the required order of operations.

Why Other Options Are Wrong:

• A: Dropping the primary key is unrelated and may introduce other integrity problems.
• B: Dropping the table is excessive; we only need to change one column.
• D: Not all listed steps are required; only removing the FK constraint is.
• E: Cache settings are irrelevant to DDL constraint rules.

Common Pitfalls:

• Forgetting indexes that may also exist on the FK column (drop or keep as needed).
• Overlooking application code that relies on the relationship.

Final Answer:

Drop the foreign key constraint.