Which Data Definition Language (DDL) command is used to change the primary key in a table?

The command used to change the primary key in a table is the ALTER TABLE command. This SQL statement allows for modifications to an existing table's structure, including adding, modifying, or deleting primary keys, columns, or constraints.

When you're working with a database and need to change a primary key—perhaps to update it to a new set of attributes or to set a different column as the primary key—ALTER TABLE provides the flexibility to do this without needing to recreate the entire table. This capability is crucial for database maintenance and helps ensure the integrity and efficiency of data management.

Other commands such as CREATE TABLE are used for creating new tables, UPDATE TABLE typically refers to modifying existing records instead of structural changes, and DROP TABLE is used for completely removing a table from the database. None of these commands are designed for changing the primary key, making ALTER TABLE the appropriate choice for this operation.