LENGTH() vs. CHAR_LENGTH() in MySQL: When Should I Use Each Function?

Discerning Length Functions: length() vs char_length()

In the realm of MySQL, two functions often arise when dealing with string lengths: length() and char_length(). It's essential to understand their fundamental differences to ensure accurate data handling.

Function Distinction:

LENGTH() gauges the string's byte count, encompassing all characters regardless of their underlying representation. On the other hand, CHAR_LENGTH() focuses on the character count, irrespective of the encoding scheme employed.

Binary Strings and Beyond:

The significance of binary strings stems from their compactness. Certain datasets demand efficient storage, and binary strings fulfill this requirement. However, binary strings come with challenges, such as character interpretation issues when stored outside of a database context.

Practical Application:

To illustrate the distinction between these functions, consider the following example:

mysql> select length('MySQL'), char_length('MySQL');
+-----------------+----------------------+
| length('MySQL') | char_length('MySQL') |
+-----------------+----------------------+
|               5 |                    5 |
+-----------------+----------------------+
1 row in set (0.01 sec)

As evident from the output, both functions return the same value (5) for the string 'MySQL' because it consists of characters each represented by a single byte. However, if a Unicode character like the Euro sign (€) is introduced, the discrepancy between the functions becomes apparent:

select length(_utf8 '€'), char_length(_utf8 '€')
--> 3, 1

Here, LENGTH() reports the byte count as 3 (since '€' is encoded in 3 bytes), while CHAR_LENGTH() correctly indicates 1 character.

Comprehending the nuances of length() and char_length() empowers you with the ability to handle string lengths with precision, ensuring the integrity of your data.

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