Data Definition Language (DDL) Flashcards

Which DDL statement creates a new database schema?

Answer: CREATE SCHEMA

CREATE SCHEMA defines a new schema (namespace) to organize database objects.

What is the effect of CREATE VIEW?

Answer: It defines a stored query presented as a virtual table

CREATE VIEW stores a query definition that behaves like a virtual table when referenced.

Which statement is used to remove a view from the database?

Answer: DROP VIEW

DROP VIEW deletes the view definition from the database.

When you ALTER a column's data type, what risk should you consider?

Answer: Existing data may be incompatible and cause errors or truncation

Changing a column's type can fail or truncate data if existing values don't fit the new type.

What does the IF EXISTS clause add to a DROP TABLE statement?

Answer: It prevents an error if the table does not exist

DROP TABLE IF EXISTS avoids raising an error when the named table is absent.

Which DDL feature lets a column automatically generate sequential numeric values?

Answer: AUTO_INCREMENT / IDENTITY / SERIAL

Auto-increment mechanisms (AUTO_INCREMENT, IDENTITY, or SERIAL depending on the system) generate sequential numbers automatically.

What does a CASCADE option on DROP TABLE typically do?

Answer: Drops dependent objects like foreign keys and views as well

CASCADE automatically drops objects that depend on the table, such as referencing constraints or views.