Which of the following is NOT a valid DDL command?

A.
UPDATE

B.
ALTER

C.
DROP

D.
CREATE

Explanation:
UPDATE is a DML command. Data-definition language (DDL) is used to specify a database schema by
a set of definitions. It is a computer
language for defining data structures. The term was first introduced in relation to the Codasyl
database model, where the schema of the
database was written in a Data Definition Language describing the records, fields, and “sets” making
up the user Data Model. The term DDL is
used in a generic sense to refer to any formal language for describing data or information structures,
like XML schemas. CREATE, DROP, and
ALTER are the major DDL commands.
Answer C, B, and D are incorrect. DROP, ALTER, and CREATE are valid DDL commands.