INNER JOIN with table aliases in SQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to select all columns from the joined tables.

SQL

SELECT * FROM employees [1] departments ON employees.department_id = departments.id;

Drag options to blanks, or click blank then click option'

AINNER JOIN

BLEFT JOIN

CRIGHT JOIN

DFULL JOIN

Attempts:

3 left

💡 Hint

Common Mistakes

Using LEFT JOIN instead of INNER JOIN returns unmatched rows from the left table.

Using FULL JOIN returns all rows from both tables, not just matches.

The INNER JOIN keyword selects records that have matching values in both tables.

2fill in blank

medium

Complete the code to assign aliases to tables and select employee names and department names.

SQL

SELECT employees.name, d.name FROM employees [1] departments d ON employees.department_id = d.id;

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ALEFT JOIN

BRIGHT JOIN

CJOIN

DINNER JOIN

Attempts:

3 left

💡 Hint

Common Mistakes

Using LEFT JOIN changes the result to include unmatched left rows.

Using RIGHT JOIN changes the result to include unmatched right rows.

The JOIN keyword is shorthand for INNER JOIN and works the same here.

3fill in blank

hard

Fix the error in the code by completing the alias for the employees table.

SQL

SELECT e.name, d.name FROM employees [1] departments d ON e.department_id = d.id;

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AAS e INNER JOIN

BINNER JOIN

CINNER JOIN AS e

De INNER JOIN

Attempts:

3 left

💡 Hint

Common Mistakes

Placing the alias after INNER JOIN causes syntax errors.

Omitting AS keyword can cause confusion but is allowed in some SQL dialects.

Use AS e to assign the alias e to employees before joining.

4fill in blank

hard

Fill both blanks to correctly alias tables and join them on matching department IDs.

SQL

SELECT [1].name, [2].name FROM employees AS e INNER JOIN departments AS d ON e.department_id = d.id;

Drag options to blanks, or click blank then click option'

Ae

Bd

Cemployees

Ddepartments

Attempts:

3 left

💡 Hint

Common Mistakes

Using full table names instead of aliases when aliases are defined.

Mixing aliases and full table names inconsistently.

Use the aliases e and d to refer to the tables in the SELECT clause.

5fill in blank

hard

Fill all three blanks to select employee name, department name, and filter by department location.

SQL

SELECT [1].name, [2].name FROM employees AS e INNER JOIN departments AS d ON e.department_id = d.id WHERE [3].location = 'New York';

Drag options to blanks, or click blank then click option'

Ae

Bd

Cdepartments

Demployees

Attempts:

3 left

💡 Hint

Common Mistakes

Using full table names instead of aliases in WHERE clause.

Filtering on the wrong table alias.

Use alias e for employees and d for departments. The location filter applies to the departments table alias d.