Data-Management-Foundations Exam Dumps : WGU Data Management – Foundations Exam

Toadd a primary key constraint after table creation, we use theALTER TABLEstatement.

Example Usage:

sql

ALTER TABLE Employees

ADD CONSTRAINT PK_Employees PRIMARY KEY (EmpID);

Thisaddsa primary key to the EmpID columnafter the table was created.

Why Other Options Are Incorrect:

Option B (CREATE TABLE) (Incorrect):Used for defining constraintsduringtable creation, not after.

Option C (UPDATE) (Incorrect):Modifiesrow values, not constraints.

Option D (INSERT INTO) (Incorrect):Used toadd datato a table, not modify constraints.

Thus, the correct answer isALTER TABLE, as itmodifies table structure to add a primary key constraint.

Anintangible entityis an entity that does not have a physical presence but still holds meaning in a database. These entities representconcepts, relationships, or abstract datathat exist in a logical sense.

Example Usage in Databases:

Customer Loyalty Status (Gold, Silver, Bronze)

Theloyalty levelis anintangible entitysince it is derived from other data (purchase history).

Online User Sessions

Asession IDexistslogically in the systembut does not have a tangible presence like a product or employee.

Why Other Options Are Incorrect:

Option A (Concrete entity) (Incorrect):No such formal term in database design.

Option B (Tangible entity) (Incorrect):Represents somethingphysical, like anemployeeorproduct.

Option D (Physical entity) (Incorrect):Refers todata stored on disk, like database tables or indexes.

Thus, the correct answer isIntangible entity, as it only exists in a logical sense within the database.

Anaggregate functionperforms acalculation over multiple rowsand returns asingle value. Examples includeSUM(), AVG(), MAX(), MIN(), and COUNT()in SQL.

Option A (Correct):Aggregate functions compute values over aset of rows, like summingtotal sales or averaging grades.

Option B (Incorrect):Selecting rows that appear in one table but not another is done usingset operations (EXCEPT or MINUS in SQL).

Option C (Incorrect):Eliminating columns is done using thePROJECToperation orSELECT with specific columns.

Option D (Incorrect):Combining rows from two tables refers to aJOIN operation, not aggregation.