Essential SQL for Aspiring Data Analysts Quiz

Test your understanding of foundational SQL concepts and strategies with these beginner-friendly questions inspired by real interview scenarios.

1. Identifying SQL Statements

   Which SQL keyword is used to retrieve data from one or more tables, for example: SELECT * FROM Employees?

   1. CHOOSE
   2. PICK
   3. SELECT
   4. RETRIEVE
   5. EXTRACT

2. Understanding Joins

   What SQL clause is used to combine rows from two tables based on a related column, such as joining 'Customers' and 'Orders' on a customer ID?

   1. UNION
   2. JOIN
   3. CONNECT
   4. MERGE
   5. LINK

3. Filtering Results

   Which keyword would you use in SQL to filter only those rows where the column 'age' is greater than 30?

   1. WHEN
   2. HAVER
   3. WHILE
   4. WHARE
   5. WHERE

4. Basic Aggregation

   To find the average value of a column called 'salary', which SQL function would you use?

   1. AVARAGE
   2. AVER
   3. COUNT
   4. AVG
   5. SUM

5. Sorting Data

   How can you sort the results in an SQL query by the 'created_at' date in descending order?

   1. SORT created_at REVERSE
   2. ORDER BY created_at DESC
   3. ORDER created_at DECREASE
   4. SORT BY created_at DOWN
   5. GROUP BY created_at DESC

6. Limiting Results

   If you only want to return the first 10 results from a table called 'users', which SQL clause should you use?

   1. LIMIT 10
   2. TAKE 10
   3. FIRST 10
   4. ROWCOUNT 10
   5. RESTRICT 10

7. Grouping Data

   When you need to calculate the sum of sales for each month, which SQL clause helps you group the data by month?

   1. BUNDLE BY
   2. SORT BY
   3. COLLECT BY
   4. BATCH BY
   5. GROUP BY

8. Working With Missing Values

   Which SQL keyword can be used to exclude rows where a column called 'email' has a NULL value?

   1. ISN'T NULL
   2. IS NOT NULL
   3. NOT IS NULL
   4. NOT EMPTY
   5. EXISTS

9. Using Subqueries

   A subquery in SQL is best described as which of the following?

   1. A query that drops a table
   2. A table inside a table
   3. A repeated table alias
   4. A query with errors
   5. A query inside another query

10. Understanding Aliases

    What is one purpose of using an alias in SQL, such as SELECT name AS employee_name FROM Employees?

    1. To give a column or table a temporary alternative name
    2. To disable indices on columns
    3. To remove duplicate rows
    4. To automate data backup
    5. To encrypt column values