String types (VARCHAR, CHAR, TEXT) in MySQL

Introduction

String types store words, sentences, or any text data in a database. They help keep information like names, descriptions, or messages.

Storing a person's name or email address.

Saving a short code or ID with fixed length.

Keeping a long article or comment text.

Recording a product description that can vary in length.

Saving a status message or note.

Syntax

MySQL

column_name VARCHAR(length)
column_name CHAR(length)
column_name TEXT

VARCHAR stores variable-length strings up to the specified length.

CHAR stores fixed-length strings and pads with spaces if shorter.

TEXT stores large amounts of text without a fixed length.

Examples

Stores a name up to 50 characters long, using only the needed space.

MySQL

name VARCHAR(50)

Stores a code exactly 5 characters long, padding with spaces if shorter.

MySQL

code CHAR(5)

Stores a long text description without a fixed length limit.

MySQL

description TEXT

Sample Program

This creates a table with three string types: VARCHAR for product name, CHAR for fixed-length SKU, and TEXT for product details. Then it inserts two products and selects all data.

MySQL

CREATE TABLE products (
  id INT PRIMARY KEY,
  name VARCHAR(30),
  sku CHAR(8),
  details TEXT
);

INSERT INTO products VALUES
(1, 'Coffee Mug', 'MUG123  ', 'A ceramic mug for coffee.'),
(2, 'Notebook', 'NOTE456 ', 'A ruled notebook with 100 pages.');

SELECT id, name, sku, details FROM products;

Important Notes

VARCHAR is good for strings that change length often, saving space.

CHAR is faster for fixed-length strings but wastes space if data is shorter.

TEXT can store very long text but may be slower to search or index.

Summary

VARCHAR stores variable-length text efficiently.

CHAR stores fixed-length text, padding shorter values.

TEXT stores large text without length limits.

Practice

1. Which MySQL string type is best for storing names that can vary in length but are usually short?

easy

A. VARCHAR

B. CHAR

C. TEXT

D. BLOB

Solution

1. Step 1: Understand string types for short variable-length text

   VARCHAR stores variable-length strings efficiently, saving space for shorter values.

2. Step 2: Compare with other types

   CHAR is fixed-length and wastes space if data varies; TEXT is for large text; BLOB is for binary data.

3. Final Answer:

   VARCHAR -> Option A

4. Quick Check:

   Variable-length short text = VARCHAR [OK]

Hint: Use VARCHAR for short, varying length text [OK]

Common Mistakes:

• Choosing CHAR wastes space for variable length
• Using TEXT for small strings is inefficient
• Confusing BLOB with text types

2. Which of the following is the correct syntax to declare a column named description that can hold up to 255 characters using VARCHAR in MySQL?

easy

A. description VARCHAR(255)

B. description CHAR(255)

C. description TEXT(255)

D. description VARCHAR

Solution

1. Step 1: Recall VARCHAR syntax

   VARCHAR requires a length in parentheses, e.g., VARCHAR(255).

2. Step 2: Check options for correct syntax

   description VARCHAR(255) uses correct syntax; description TEXT(255) uses wrong type; description CHAR(255) uses fixed-length CHAR; description VARCHAR misses length.

3. Final Answer:

   description VARCHAR(255) -> Option A

4. Quick Check:

   VARCHAR needs length in parentheses [OK]

Hint: Always specify length in parentheses for VARCHAR [OK]

Common Mistakes:

• Omitting length for VARCHAR
• Adding length to TEXT type
• Confusing CHAR and VARCHAR syntax

3. Given the table users with a username CHAR(10) column, what will be the result of this query?

INSERT INTO users (username) VALUES ('bob');
SELECT username, LENGTH(username) FROM users WHERE username = 'bob';

medium

A. username = 'bob', LENGTH(username) = 3

B. username = 'bob ', LENGTH(username) = 3

C. username = 'bob', LENGTH(username) = 10

D. username = 'bob ', LENGTH(username) = 10

Solution

1. Step 1: Understand CHAR behavior on insert

   CHAR(10) stores fixed length strings, padding with spaces to length 10.

2. Step 2: Check LENGTH function on padded string

   LENGTH counts all characters including spaces, so LENGTH('bob ') = 10.

3. Final Answer:

   username = 'bob ', LENGTH(username) = 10 -> Option D

4. Quick Check:

   CHAR pads with spaces, LENGTH counts all chars [OK]

Hint: CHAR pads with spaces; LENGTH counts all characters [OK]

Common Mistakes:

• Assuming LENGTH returns 3 for 'bob'
• Ignoring space padding in CHAR
• Confusing CHAR with VARCHAR behavior

4. You have a column defined as notes TEXT. You try to insert a string longer than 65,535 characters and get an error. What is the likely cause and how to fix it?

medium

A. VARCHAR max length is 65,535; use TEXT instead

B. TEXT type has a max length of 65,535 bytes; use MEDIUMTEXT for longer text

C. CHAR cannot store large text; use VARCHAR(65535)

D. TEXT type has no length limit; error is from syntax

Solution

1. Step 1: Recall TEXT max size limits

   TEXT can store up to 65,535 bytes; longer text causes error.

2. Step 2: Choose correct larger text type

   MEDIUMTEXT supports up to 16 million bytes, suitable for longer text.

3. Final Answer:

   TEXT type has a max length of 65,535 bytes; use MEDIUMTEXT for longer text -> Option B

4. Quick Check:

   TEXT max 65,535 bytes; MEDIUMTEXT for more [OK]

Hint: TEXT max 65k chars; use MEDIUMTEXT for bigger text [OK]

Common Mistakes:

• Thinking TEXT has unlimited length
• Using VARCHAR for very large text
• Confusing CHAR with TEXT size limits

5. You want to store user comments that can be very long but also want to optimize storage for short comments. Which MySQL string type should you choose and why?

hard

A. Use VARCHAR(500) to save space for short comments and allow long ones

B. Use CHAR(500) to fix length and speed up queries

C. Use TEXT because it stores large text without fixed length

D. Use VARCHAR(65535) to cover all comment lengths

Solution

1. Step 1: Consider storage needs for very long text

   VARCHAR max length is limited (usually 65,535 bytes total row size), so very long comments may exceed it.

2. Step 2: Evaluate TEXT type for large variable text

   TEXT stores large text efficiently without fixed length and supports very long strings.

3. Final Answer:

   Use TEXT because it stores large text without fixed length -> Option C

4. Quick Check:

   Large variable text = TEXT type [OK]

Hint: Use TEXT for very long text, VARCHAR for shorter variable text [OK]

Common Mistakes:

• Choosing fixed-length CHAR wastes space
• Using VARCHAR too large causes errors
• Assuming VARCHAR can store unlimited text