TRIM, LTRIM, RTRIM in MySQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to remove spaces from both ends of the string ' hello '.

MySQL

SELECT [1]('  hello  ') AS trimmed;

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

ALTRIM

BRTRIM

CTRIM

DSUBSTR

Attempts:

3 left

💡 Hint

Common Mistakes

Using LTRIM or RTRIM removes spaces only from one side.

Using SUBSTR does not remove spaces.

The TRIM function removes spaces from both the left and right ends of a string.

2fill in blank

medium

Complete the code to remove spaces only from the left side of the string ' world '.

MySQL

SELECT [1]('  world  ') AS left_trimmed;

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

ATRIM

BREPLACE

CRTRIM

DLTRIM

Attempts:

3 left

💡 Hint

Common Mistakes

Using TRIM removes spaces from both sides, not just left.

Using RTRIM removes spaces from the right side.

The LTRIM function removes spaces only from the left (start) of the string.

3fill in blank

hard

Fix the error in the code to remove spaces only from the right side of the string ' test '.

MySQL

SELECT [1]('  test  ') AS right_trimmed;

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

ARTRIM

BTRIM

CLTRIM

DLEFT

Attempts:

3 left

💡 Hint

Common Mistakes

Using LTRIM removes spaces from the left side.

Using TRIM removes spaces from both sides.

The RTRIM function removes spaces only from the right (end) of the string.

4fill in blank

hard

Fill both blanks to remove spaces from the left and right sides of the string ' data ' using nested functions.

MySQL

SELECT [1]([2]('  data  ')) AS trimmed;

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

ALTRIM

BTRIM

CRTRIM

DREPLACE

Attempts:

3 left

💡 Hint

Common Mistakes

Using TRIM inside LTRIM is redundant.

Using REPLACE does not remove spaces properly.

Using LTRIM outside RTRIM removes spaces from right first, then left.

5fill in blank

hard

Fill all three blanks to remove a specific character '#' from both ends of the string '#example#' using TRIM syntax.

MySQL

SELECT TRIM([1] [2] [3] '#example#') AS cleaned;

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

A'#'

BBOTH

CFROM

DLTRIM

Attempts:

3 left

💡 Hint

Common Mistakes

Using LTRIM instead of TRIM for both sides.

Wrong order of keywords in TRIM syntax.

The syntax TRIM(BOTH '#' FROM string) removes '#' from both ends.

Practice

1. What does the TRIM function do in MySQL?

easy

A. Removes spaces or specified characters from both ends of a string

B. Removes spaces only from the start of a string

C. Removes spaces only from the end of a string

D. Replaces spaces inside the string with underscores

Solution

1. Step 1: Understand the purpose of TRIM

   The TRIM function is designed to remove unwanted spaces or characters from the start and end of a string.

2. Step 2: Compare with LTRIM and RTRIM

   LTRIM removes only from the left, RTRIM only from the right, but TRIM does both ends.

3. Final Answer:

   Removes spaces or specified characters from both ends of a string -> Option A

4. Quick Check:

   TRIM = both ends removal [OK]

Hint: TRIM cleans both sides of spaces or chars [OK]

Common Mistakes:

• Confusing TRIM with LTRIM or RTRIM
• Thinking TRIM removes spaces inside the string
• Assuming TRIM only removes spaces from one side

2. Which of the following is the correct syntax to remove spaces from the left side of a string ' hello' in MySQL?

easy

A. RTRIM(' hello')

B. LTRIM(' hello')

C. TRIM(' hello')

D. REMOVE_LEFT(' hello')

Solution

1. Step 1: Identify the function for left-side trimming

   LTRIM is the MySQL function that removes spaces from the start (left side) of a string.

2. Step 2: Check other options

   RTRIM removes spaces from the right side, TRIM removes from both ends, and REMOVE_LEFT is not a valid MySQL function.

3. Final Answer:

   LTRIM(' hello') -> Option B

4. Quick Check:

   LTRIM = left side spaces removed [OK]

Hint: Use LTRIM() to remove left spaces [OK]

Common Mistakes:

• Using RTRIM instead of LTRIM
• Using TRIM when only left spaces needed
• Using non-existent functions like REMOVE_LEFT

3. What is the output of this query?
SELECT CONCAT('[', TRIM(' abc '), ']') AS result;

medium

A. [abc]

B. [ abc ]

C. [abc ]

D. [ abc]

Solution

1. Step 1: Understand TRIM effect on the string

   TRIM removes spaces from both the start and end of ' abc ', resulting in 'abc'.

2. Step 2: Apply CONCAT with brackets

   Concatenating '[' + 'abc' + ']' results in '[abc]'.

3. Final Answer:

   [abc] -> Option A

4. Quick Check:

   TRIM removes spaces both ends = '[abc]' [OK]

Hint: TRIM removes spaces both ends, so output is '[abc]' [OK]

Common Mistakes:

• Thinking TRIM removes spaces only from one side
• Ignoring spaces inside the string
• Confusing CONCAT output formatting

4. Identify the error in this query:
SELECT LTRIM(' test') FROM dual WHERE RTRIM('test ') = 'test';

medium

A. No error, query runs correctly

B. RTRIM cannot be used in WHERE clause

C. LTRIM and RTRIM functions are misspelled

D. Using FROM dual is invalid in MySQL

Solution

1. Step 1: Check the use of FROM dual in MySQL

   MySQL does not require or support the FROM dual syntax; it is used in Oracle.

2. Step 2: Verify function usage and WHERE clause

   LTRIM and RTRIM are valid functions and can be used in WHERE clauses in MySQL.

3. Final Answer:

   Using FROM dual is invalid in MySQL -> Option D

4. Quick Check:

   FROM dual is Oracle-specific, not MySQL [OK]

Hint: MySQL does not use FROM dual [OK]

Common Mistakes:

• Assuming FROM dual works in MySQL
• Thinking RTRIM can't be in WHERE clause
• Misspelling function names

5. You have a table users with a column username that may have extra spaces at the start or end. Which query correctly updates the table to remove all leading and trailing spaces from username?

hard

A. UPDATE users SET username = LTRIM(username);

B. UPDATE users SET username = RTRIM(username);

C. UPDATE users SET username = TRIM(username);

D. UPDATE users SET username = REPLACE(username, ' ', '');

Solution

1. Step 1: Understand how to remove spaces from both ends

   TRIM removes spaces from both the start and end of a string in one call.

2. Step 2: Check LTRIM and RTRIM options

   LTRIM removes only leading spaces, RTRIM only trailing spaces. Neither handles both ends alone.

3. Step 3: Check REPLACE option

   REPLACE removes all spaces inside the string, not just at ends, which is incorrect here.

4. Final Answer:

   UPDATE users SET username = TRIM(username); -> Option C

5. Quick Check:

   TRIM cleans both ends simply [OK]

Hint: Use TRIM() to clean both ends in one step [OK]

Common Mistakes:

• Using LTRIM which only removes leading spaces
• Using RTRIM which only removes trailing spaces
• Using REPLACE which removes all spaces