SQL and Database Concepts Quiz

Which operator combines the result sets of two or more SELECT statements and returns all rows, including duplicates?

• UNION

• UNION ALL

• INTERSECT

• EXCEPT

The most widely used data model today, which organizes data in tables with rows and columns, is the:

• Hierarchical Model

• Network Model

• Relational Model

• Object-Oriented Model

The `BETWEEN` operator is used in a `WHERE` clause to:

• Select values that are exactly one of two specified values

• Indicate values that fall within a specified range (inclusive)

• Select values that are outside a specified range

• Compare two string values for partial matches

In the three-schema architecture, which level describes how a record is stored?

• External Level

• Conceptual Level

• Physical Level

• View Level

The `IF UPDATE (column_name)` clause within a trigger allows you to:

• Update a specific column when the trigger fires.

• Check if a specific column was affected by an UPDATE statement that fired the trigger.

• Prevent updates to a specific column.

• Define a trigger that only fires when a specific column is updated.

Which type of JOIN selects records that have matching values in both tables?

• INNER JOIN

• LEFT OUTER JOIN

• RIGHT OUTER JOIN

• FULL OUTER JOIN

The `EXISTS` operator is used with a subquery to:

• Compare a value to a set of values returned by the subquery

• Test for the existence of any record in the subquery's result

• Return all records from the subquery

• Check if a subquery returns a NULL value

A subquery that is evaluated once for each row processed by the parent statement is called a:

• Simple Subquery

• Nested Subquery

• Correlated Subquery

• Inline Subquery

The DDL command used to remove a table completely from the database, destroying its structure and data, is:

• DELETE TABLE

• DROP TABLE

• REMOVE TABLE

• ERASE TABLE

Which data type category is used for storing data objects like files and images?

• String Data

• Numeric Data

• Temporal Data

• Large Objects (LOBs)