Introduction to SQL

1. Which of the following statements are true about relational databases and SQLite?

   Choose as many answers as you see fit.

   Referencing one table's primary key in another table lets you model relationships between tables.

   A SQLite database consists of columns, which consist of tables and rows.

   Every data table must have at least one foreign key.

   Rows contain the individual items in the database.

2. It is optional to end a SQL statement with a semicolon.

   True

   False

3. If you want to calculate the sum of all values for a database column, what do you use?

   Aggregate function

   WHERE clause

   DISTINCT keyword

   LIMIT clause

4. Which SELECT statement returns the number of unique email addresses for messages in the spam folder?

   SELECT COUNT(DISTINCT folder) FROM email WHERE spam != sender;

   SELECT DISTINCT COUNT(sender) FROM email WHERE folder = 'spam';

   SELECT COUNT(DISTINCT sender) FROM email WHERE folder = 'spam';

   SELECT DISTINCT COUNT('spam') FROM email WHERE sender = folder;

5. The SQL statement SELECT * FROM contacts WHERE name LIKE '%Milton' returns all rows where the value of the name column begins with Milton.

   True

   False

6. Which of the following statements are true about GROUP BY and ORDER BY?

   Choose as many answers as you see fit.

   The ORDER BY clause comes before the GROUP BY clause.

   In an ORDER BY clause, descending order is the default.

   If a query contains a GROUP BY clause, it overrides the ORDER BY clause.

   ORDER BY and GROUP BY clauses can both accept multiple columns.

7. The WHERE condition NOT read = false and the WHERE condition read != true are equivalent.

   True

   False

8. The LIMIT clause LIMIT 30 SKIP 60 returns:

   60 rows

   Rows 31 through 60

   Rows 61 through 90

   90 rows

9. An UPDATE statement uses a ___ clause to assign values for columns.

   WHERE

   SET

   ASSIGN

   LIKE

10. UPDATE and DELETE statements can include a WHERE clause and can affect multiple rows.

    True

    False

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