AND, OR, NOT logical operators in MySQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to select rows where age is greater than 18 and status is 'active'.

MySQL

SELECT * FROM users WHERE age > 18 [1] status = 'active';

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

AXOR

BAND

CNOT

DOR

Attempts:

3 left

💡 Hint

Common Mistakes

Using OR instead of AND selects rows that meet only one condition.

Using NOT here would negate a single condition, not combine two.

The AND operator ensures both conditions must be true for a row to be selected.

2fill in blank

medium

Complete the code to select rows where city is 'New York' or city is 'Los Angeles'.

MySQL

SELECT * FROM customers WHERE city = 'New York' [1] city = 'Los Angeles';

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

AXOR

BAND

COR

DNOT

Attempts:

3 left

💡 Hint

Common Mistakes

Using AND would require the city to be both places at once, which is impossible.

Using NOT would negate a condition, not combine two.

The OR operator selects rows where either condition is true.

3fill in blank

hard

Fix the error in the code to select rows where NOT status is 'inactive'.

MySQL

SELECT * FROM accounts WHERE [1] status = 'inactive';

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

ANOT

BAND

COR

DXOR

Attempts:

3 left

💡 Hint

Common Mistakes

Using AND or OR here changes the logic and does not negate the condition.

XOR is not used for negation.

The NOT operator negates the condition, selecting rows where status is not 'inactive'.

4fill in blank

hard

Fill both blanks to select rows where age is greater than 30 and city is not 'Chicago'.

MySQL

SELECT * FROM employees WHERE age > 30 [1] [2] city = 'Chicago';

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

AAND

BOR

CNOT

DXOR

Attempts:

3 left

💡 Hint

Common Mistakes

Using OR would select rows with age > 30 or city not Chicago, which is different logic.

Placing NOT after city without AND causes syntax errors.

Use AND to combine conditions and NOT to negate the city condition.

5fill in blank

hard

Fill all three blanks to select rows where (salary > 50000 or position is 'Manager') and department is not 'Sales'.

MySQL

SELECT * FROM staff WHERE (salary > 50000 [1] position = 'Manager') [2] [3] department = 'Sales';

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

AAND

BOR

CNOT

DXOR

Attempts:

3 left

💡 Hint

Common Mistakes

Using AND inside parentheses changes the logic incorrectly.

Forgetting NOT before department causes wrong results.

Using XOR is not appropriate here.

Use OR inside parentheses to select salary or position, then AND to combine with the negated department condition using NOT.

Practice

1. Which logical operator in MySQL requires all conditions to be true for the whole expression to be true?

easy

A. XOR

B. OR

C. NOT

D. AND

Solution

1. Step 1: Understand AND operator behavior

   The AND operator returns true only if every condition joined by it is true.

2. Step 2: Compare with other operators

   OR requires at least one true condition, NOT reverses truth, XOR is exclusive or.

3. Final Answer:

   AND -> Option D

4. Quick Check:

   AND means all true = A [OK]

Hint: AND means all conditions must be true [OK]

Common Mistakes:

• Confusing AND with OR
• Thinking NOT requires all true
• Mixing XOR with AND

2. Which of the following is the correct syntax to select rows where age is greater than 18 and status is 'active'?

easy

A. SELECT * FROM users WHERE age > 18 AND status = 'active';

B. SELECT * FROM users WHERE NOT age > 18 AND status = 'active';

C. SELECT * FROM users WHERE age > 18 OR status = 'active';

D. SELECT * FROM users WHERE age > 18 NOT status = 'active';

Solution

1. Step 1: Identify correct logical operator for both conditions

   We want rows where both age > 18 and status = 'active' are true, so use AND.

2. Step 2: Check syntax correctness

   SELECT * FROM users WHERE age > 18 AND status = 'active'; uses AND correctly and has valid SQL syntax.

3. Final Answer:

   SELECT * FROM users WHERE age > 18 AND status = 'active'; -> Option A

4. Quick Check:

   AND joins conditions correctly = C [OK]

Hint: Use AND to combine multiple true conditions [OK]

Common Mistakes:

• Using OR instead of AND
• Incorrect NOT placement
• Syntax errors like missing AND

3. Given the table employees with columns department and salary, what rows will this query return?

SELECT * FROM employees WHERE department = 'Sales' OR salary > 50000 AND NOT department = 'HR';

medium

A. Rows where department is 'Sales' or salary > 50000 or department is not 'HR'

B. Rows where department is 'Sales' and salary > 50000 and department is not 'HR'

C. Rows where department is 'Sales' or salary > 50000 and department is not 'HR'

D. Rows where salary > 50000 only

Solution

1. Step 1: Understand operator precedence

   AND has higher precedence than OR, so condition is: department = 'Sales' OR (salary > 50000 AND NOT department = 'HR').

2. Step 2: Interpret the conditions

   Rows match if department is 'Sales', or if salary > 50000 and department is not 'HR'.

3. Final Answer:

   Rows where department is 'Sales' or salary > 50000 and department is not 'HR' -> Option C

4. Quick Check:

   AND before OR, NOT reverses condition = B [OK]

Hint: AND binds tighter than OR; use parentheses to clarify [OK]

Common Mistakes:

• Ignoring operator precedence
• Misreading NOT placement
• Assuming OR applies to all conditions

4. Identify the error in this query:

SELECT * FROM orders WHERE NOT order_date > '2023-01-01' AND status = 'shipped' OR;

medium

A. Incorrect use of NOT operator

B. Missing condition after OR

C. AND should be OR

D. order_date comparison syntax error

Solution

1. Step 1: Check query syntax

   The query ends with OR but no condition follows it, causing syntax error.

2. Step 2: Verify other parts

   NOT and AND usage is correct; order_date comparison is valid.

3. Final Answer:

   Missing condition after OR -> Option B

4. Quick Check:

   OR must have two conditions = A [OK]

Hint: OR must always connect two conditions [OK]

Common Mistakes:

• Leaving OR without a following condition
• Misplacing NOT operator
• Confusing AND and OR usage

5. You want to select all customers who are NOT in the 'VIP' group AND have made a purchase OR have a balance greater than 1000. Which query correctly expresses this logic?

hard

A. SELECT * FROM customers WHERE NOT group = 'VIP' AND (purchases > 0 OR balance > 1000);

B. SELECT * FROM customers WHERE NOT (group = 'VIP' AND purchases > 0) OR balance > 1000;

C. SELECT * FROM customers WHERE NOT group = 'VIP' AND purchases > 0 OR balance > 1000;

D. SELECT * FROM customers WHERE NOT group = 'VIP' OR purchases > 0 AND balance > 1000;

Solution

1. Step 1: Translate the logic into conditions

   We want customers NOT in 'VIP' group AND (have purchases OR balance > 1000).

2. Step 2: Check operator precedence and parentheses

   AND has higher precedence than OR, so parentheses around (purchases > 0 OR balance > 1000) ensure correct grouping.

3. Step 3: Evaluate options

   SELECT * FROM customers WHERE NOT group = 'VIP' AND (purchases > 0 OR balance > 1000); correctly uses NOT on group, AND with grouped OR conditions. Others misplace parentheses or NOT.

4. Final Answer:

   SELECT * FROM customers WHERE NOT group = 'VIP' AND (purchases > 0 OR balance > 1000); -> Option A

5. Quick Check:

   NOT group, AND grouped OR = D [OK]

Hint: Use parentheses to group OR conditions with AND [OK]

Common Mistakes:

• Missing parentheses causing wrong logic
• Applying NOT to wrong part
• Confusing AND and OR precedence