CHAR_LENGTH
Description
The CHAR_LENGTH function calculates the number of characters (not bytes) in a string. For multi-byte characters (such as Chinese characters), it returns the number of characters.
Currently only supports UTF-8 encoding.
Alias
- CHARACTER_LENGTH
Syntax
CHAR_LENGTH(<str>)
Parameters
| Parameter | Description |
|---|---|
<str> | The string to calculate character length. Type: VARCHAR |
Return Value
Returns INT type, representing the number of characters in the string.
Special cases:
- If the parameter is NULL, returns NULL
- Empty string returns 0
- Multi-byte UTF-8 characters each count as 1 character
Examples
- English characters
SELECT CHAR_LENGTH('hello');
+----------------------+
| char_length('hello') |
+----------------------+
| 5 |
+----------------------+
- Chinese characters (each Chinese character counts as one character)
SELECT CHAR_LENGTH('中国');
+----------------------+
| char_length('中国') |
+----------------------+
| 2 |
+----------------------+
- NULL value handling
SELECT CHAR_LENGTH(NULL);
+--------------------+
| char_length(NULL) |
+--------------------+
| NULL |
+--------------------+
- Comparison with LENGTH function (LENGTH returns byte count)
SELECT CHAR_LENGTH('中国') AS char_len, LENGTH('中国') AS byte_len;
+----------+----------+
| char_len | byte_len |
+----------+----------+
| 2 | 6 |
+----------+----------+
