Database Management & SQL Flashcards

A tobacco retailer needs to find products where the brand name starts with 'Don'. Which SQL pattern matches this?

Answer: WHERE brand LIKE 'Don%'

The LIKE operator with a % wildcard matches any string beginning with the specified characters.

What does the SQL NULL value represent in a tobacco retail database?

Answer: The absence of any value

NULL in SQL specifically means that no data value is stored for that field — it is not the same as zero or empty string.

Which SQL statement is used to remove an entire table and its structure from a tobacco retail database?

Answer: DROP TABLE products

DROP TABLE permanently deletes the table and all its data from the database.

A store tracks tobacco sales by month. Which SQL function extracts the month from a date column named sale_date?

Answer: MONTH(sale_date)

The MONTH() function extracts the month component from a date value in most SQL databases.

In a tobacco retail database, a transaction table has a column 'quantity' that should never be negative. Which constraint enforces this?

Answer: CHECK (quantity >= 0)

A CHECK constraint validates that column values meet a specified condition before allowing insertion or update.

Which type of SQL index is most commonly used to speed up lookups on a product_id column in a large tobacco inventory table?

Answer: Clustered index

A clustered index physically sorts table data by the indexed column, making lookups on that column very fast.

A SQL subquery is used inside a WHERE clause when querying tobacco sales. What does a subquery do?

Answer: Runs a query nested within another query to supply filter values

A subquery is a SELECT statement embedded within another SQL statement to provide values for filtering or comparison.