EXPLAIN query analysis in MySQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to show the execution plan of a SELECT query.

MySQL

EXPLAIN [1] * FROM employees;

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AUPDATE

BDELETE

CSELECT

DINSERT

Attempts:

3 left

💡 Hint

Common Mistakes

Using EXPLAIN with DELETE or UPDATE without SELECT

Forgetting to put SELECT after EXPLAIN

The EXPLAIN statement is used with a SELECT query to show how MySQL executes it.

2fill in blank

medium

Complete the code to analyze a query filtering by department.

MySQL

EXPLAIN SELECT * FROM employees WHERE department [1] 'Sales';

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ABETWEEN

BLIKE

CIN

D=

Attempts:

3 left

💡 Hint

Common Mistakes

Using LIKE without wildcards

Using IN with a single value

The '=' operator is used to filter rows where the department exactly matches 'Sales'.

3fill in blank

hard

Fix the error in the EXPLAIN query by completing the missing keyword.

MySQL

EXPLAIN [1] * FROM employees WHERE salary > 50000;

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ASELECT

BFROM

CTABLE

DSHOW

Attempts:

3 left

💡 Hint

Common Mistakes

Using EXPLAIN FROM instead of EXPLAIN SELECT

Omitting SELECT keyword

EXPLAIN must be followed by a SELECT statement to analyze the query plan.

4fill in blank

hard

Fill both blanks to analyze a query that orders employees by hire date.

MySQL

EXPLAIN SELECT * FROM employees ORDER BY [1] [2];

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Ahire_date

Bsalary

CASC

DDESC

Attempts:

3 left

💡 Hint

Common Mistakes

Using salary instead of hire_date

Using DESC when ascending order is intended

The query orders employees by their hire date in ascending order.

5fill in blank

hard

Fill all three blanks to analyze a query that joins employees and departments.

MySQL

EXPLAIN SELECT e.name, d.name FROM employees e [1] departments d ON e.[2] = d.[3];

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AJOIN

Bdepartment_id

Cid

DLEFT JOIN

Attempts:

3 left

💡 Hint

Common Mistakes

Using JOIN instead of LEFT JOIN

Mixing column names in ON clause

The query uses a LEFT JOIN to combine employees with departments matching on department_id and id.