First query execution in MySQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to select all columns from the table named 'employees'.

MySQL

SELECT [1] FROM employees;

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

A*

BALL

Ccolumns

Deverything

Attempts:

3 left

💡 Hint

Common Mistakes

Using words like ALL or columns instead of *

Forgetting to specify what to select

The asterisk (*) means select all columns from the table.

2fill in blank

medium

Complete the code to select only the 'name' column from the 'employees' table.

MySQL

SELECT [1] FROM employees;

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

Aname

Ball

Cnames

Demployee_name

Attempts:

3 left

💡 Hint

Common Mistakes

Using plural or different column names like 'names' or 'employee_name'

Using keywords like 'all' instead of a column name

Use the exact column name 'name' to select that column.

3fill in blank

hard

Fix the error in the query to select the 'salary' column from 'employees'.

MySQL

SELECT [1] FROM employees;

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

Asalaries

Bsal

CSalary

Dsalary

Attempts:

3 left

💡 Hint

Common Mistakes

Using plural or abbreviated column names

Using incorrect capitalization if case-sensitive

The correct column name is 'salary'. Using the exact column name avoids errors.

4fill in blank

hard

Fill both blanks to select the 'name' and 'salary' columns from 'employees'.

MySQL

SELECT [1], [2] FROM employees;

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

Aname

Bsalary

Cage

Ddepartment

Attempts:

3 left

💡 Hint

Common Mistakes

Using columns not in the table

Forgetting the comma between column names

To select multiple columns, list them separated by commas.

5fill in blank

hard

Fill all three blanks to select 'name', 'salary', and 'department' columns from 'employees'.

MySQL

SELECT [1], [2], [3] FROM employees;

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

Aname

Bsalary

Cdepartment

Dage

Attempts:

3 left

💡 Hint

Common Mistakes

Including columns not in the table

Missing commas between column names

List all desired columns separated by commas in the SELECT statement.

Practice

1. What does the SELECT statement do in MySQL?

easy

A. It retrieves data from a database table.

B. It deletes data from a database table.

C. It updates data in a database table.

D. It creates a new database table.

Solution

1. Step 1: Understand the purpose of SELECT

   The SELECT statement is used to get or read data from a table in a database.

2. Step 2: Compare with other SQL commands

   DELETE removes data, UPDATE changes data, and CREATE makes new tables, so they are different from SELECT.

3. Final Answer:

   It retrieves data from a database table. -> Option A

4. Quick Check:

   SELECT = retrieve data [OK]

Hint: SELECT means get data from a table [OK]

Common Mistakes:

• Confusing SELECT with DELETE or UPDATE
• Thinking SELECT creates tables
• Mixing SELECT with data modification commands

2. Which of the following is the correct syntax to select all columns from a table named users?

easy

A. SELECT users FROM *;

B. SELECT * FROM users;

C. SELECT * users FROM;

D. FROM users SELECT *;

Solution

1. Step 1: Recall the basic SELECT syntax

   The correct syntax to get all columns is: SELECT * FROM table_name;

2. Step 2: Check each option

   SELECT * FROM users; matches the correct syntax. Others have wrong order or misplaced keywords.

3. Final Answer:

   SELECT * FROM users; -> Option B

4. Quick Check:

   SELECT * FROM table_name; is correct [OK]

Hint: SELECT * FROM table_name; gets all columns [OK]

Common Mistakes:

• Swapping SELECT and FROM keywords
• Omitting the FROM keyword
• Placing * in wrong position

3. Given a table products with columns id, name, and price, what will this query return?

SELECT name FROM products;

medium

A. All product names from the products table.

B. All product prices from the products table.

C. All columns from the products table.

D. An error because price column is missing.

Solution

1. Step 1: Understand the SELECT clause

   The query selects only the 'name' column from the products table.

2. Step 2: Check what is returned

   It returns all rows but only the 'name' column values, not price or id.

3. Final Answer:

   All product names from the products table. -> Option A

4. Quick Check:

   SELECT name returns names only [OK]

Hint: SELECT column_name returns that column's data [OK]

Common Mistakes:

• Assuming all columns are returned
• Thinking missing columns cause errors
• Confusing column names in SELECT

4. What is wrong with this query?

SELECT FROM users;

medium

A. FROM keyword should be after WHERE.

B. Table name is incorrect.

C. Missing column names or * after SELECT.

D. SELECT cannot be used with FROM.

Solution

1. Step 1: Check the SELECT syntax

   SELECT must be followed by column names or * to specify what to retrieve.

2. Step 2: Identify the error in the query

   The query has SELECT but no columns or * after it, causing a syntax error.

3. Final Answer:

   Missing column names or * after SELECT. -> Option C

4. Quick Check:

   SELECT needs columns or * [OK]

Hint: Always specify columns or * after SELECT [OK]

Common Mistakes:

• Leaving SELECT empty
• Misplacing FROM keyword
• Thinking FROM is optional

5. You want to see all columns from a table employees but only for employees with the job title 'Manager'. Which query should you use?

hard

A. SELECT * WHERE job_title = 'Manager' FROM employees;

B. SELECT job_title FROM employees WHERE job_title = 'Manager';

C. SELECT * FROM employees;

D. SELECT * FROM employees WHERE job_title = 'Manager';

Solution

1. Step 1: Identify the need to filter rows

   We want all columns but only rows where job_title is 'Manager', so we need a WHERE clause.

2. Step 2: Check query syntax and logic

   SELECT * FROM employees WHERE job_title = 'Manager'; correctly uses SELECT * FROM employees WHERE job_title = 'Manager'; which returns all columns filtered by job title.

3. Final Answer:

   SELECT * FROM employees WHERE job_title = 'Manager'; -> Option D

4. Quick Check:

   Use WHERE to filter rows [OK]

Hint: Use WHERE to filter rows after FROM [OK]

Common Mistakes:

• Omitting WHERE clause for filtering
• Placing WHERE before FROM
• Selecting only job_title instead of all columns