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SQL LENGTH Function

Quick summary: The SQL LENGTH() function returns the length of a string in bytes.

SQL LENGTH Syntax 

LENGTH(string)
SQL

SQL LENGTH Basic examples 

SELECT LENGTH('hello');
SQL
Output:
5

Counts bytes in a string.

SQL LENGTH Real-world usage 

SELECT * FROM users WHERE LENGTH(password) < 8;
SQL
Output:
Users with short passwords

Validates data length.

SQL LENGTH Edge cases 

SELECT LENGTH('🚀');
SQL
Output:
4

Multibyte characters count as multiple bytes.

SQL LENGTH Common mistakes

Using LENGTH for character count

LENGTH counts bytes, not characters.

Incorrect
LENGTH(name)
Correct
CHAR_LENGTH(name)

Use CHAR_LENGTH for UTF-8 strings.

SQL LENGTH Frequently Asked Questions

What does LENGTH() do in SQL?

Returns the length of a string.

Use case of LENGTH()?

Validating string size.

Counts bytes or characters?

Depends on DB.

Common mistake?

Confusing with CHAR_LENGTH().

Return type?

Integer.

Handles NULL?

Returns NULL.

Performance?

Fast.

Used in WHERE?

Yes.

Alternative?

CHAR_LENGTH.

Used in validation?

Yes.

Supports multibyte?

Depends on function.

Best practice?

Use correct function for encoding.

SQL LENGTH Related SQL Keywords