LENGTH and CHAR_LENGTH in MySQL - Step-by-Step Execution

Concept Flow - LENGTH and CHAR_LENGTH

Input String

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Output: Byte Count

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Input String

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Output: Character Count

LENGTH counts bytes in a string, CHAR_LENGTH counts characters. For ASCII, both are same; for multibyte (e.g., UTF-8), LENGTH can be larger.

Execution Sample

MySQL

SELECT LENGTH('hello'), CHAR_LENGTH('hello');
SELECT LENGTH('café'), CHAR_LENGTH('café');

Shows difference between LENGTH and CHAR_LENGTH on ASCII and accented characters.

Execution Table

Step	Input String	Function	Result	Explanation
1	'hello'	LENGTH('hello')	5	Each ASCII character is 1 byte, total 5 bytes
2	'hello'	CHAR_LENGTH('hello')	5	5 characters in string
3	'café'	LENGTH('café')	5	é is 2 bytes in UTF-8, total bytes = 4 + 1 = 5
4	'café'	CHAR_LENGTH('café')	4	4 characters total, counting accented as one character

💡 All function calls complete, results show byte vs character counts

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	Final
Input String	''	'hello'	'hello'	'café'	'café'	'café'
LENGTH Result	null	5	5	5	5	5
CHAR_LENGTH Result	null	-	5	-	4	4

Key Moments - 2 Insights

Why does LENGTH('café') return 5 but CHAR_LENGTH('café') returns 4?

Because LENGTH counts bytes, and 'é' uses 2 bytes in UTF-8, so total bytes are 5. CHAR_LENGTH counts characters, so 'café' has 4 characters.

Are LENGTH and CHAR_LENGTH always the same?

No, they are the same only for single-byte character sets like ASCII. For multibyte characters, LENGTH counts bytes, CHAR_LENGTH counts characters.

Visual Quiz - 3 Questions

Look at the execution table, what is the LENGTH('hello') result at step 1?

A 6

B 5

C 4

D 1

💡 Hint

Check the 'Result' column in row with Step 1 in execution_table

At which step does CHAR_LENGTH return 4?

A Step 4

B Step 2

C Step 3

D Step 1

💡 Hint

Look at the 'Function' and 'Result' columns in execution_table rows

If the input string was only ASCII characters, how would LENGTH and CHAR_LENGTH compare?

A LENGTH would be greater than CHAR_LENGTH

B CHAR_LENGTH would be greater than LENGTH

C Both would be equal

D Cannot determine

💡 Hint

Refer to the concept_flow description about ASCII characters

Concept Snapshot

LENGTH(string) returns number of bytes in string.
CHAR_LENGTH(string) returns number of characters.
For ASCII, both are equal.
For multibyte chars (e.g., UTF-8), LENGTH >= CHAR_LENGTH.
Use CHAR_LENGTH to count characters, LENGTH for bytes.

Full Transcript

This lesson shows how LENGTH and CHAR_LENGTH functions work in MySQL. LENGTH counts the number of bytes in a string, while CHAR_LENGTH counts the number of characters. For example, the string 'hello' has 5 bytes and 5 characters, so both functions return 5. But for 'café', LENGTH returns 5 because the accented 'é' uses 2 bytes in UTF-8 encoding, while CHAR_LENGTH returns 4 because there are 4 characters. This difference is important when working with multibyte character sets. Remember, LENGTH counts bytes, CHAR_LENGTH counts characters.