TRIM

Description

The TRIM function is used to remove consecutive spaces or specified strings from both ends of a string. If the second parameter is not specified, leading and trailing spaces are removed; if specified, the function removes the specified complete string from both ends.

Syntax

TRIM(<str>[, <rhs>])

Parameters

Parameter	Description
<str>	The string to be processed. Type: VARCHAR
<rhs>	Optional parameter, characters to be trimmed from both ends. Type: VARCHAR

Return Value

Returns a value of type VARCHAR.

Special cases:

• If any parameter is NULL, NULL is returned
• If rhs is not specified, removes leading and trailing spaces
• If rhs is specified, removes the complete rhs string from both ends (not character-by-character)

Examples

1. Remove leading and trailing spaces

SELECT trim('   ab d   ') str;

+------+
| str  |
+------+
| ab d |
+------+

2. Remove specified strings from both ends — trim(str, rhs) repeatedly strips <rhs> from both the leading and trailing ends of <str> until neither end starts/ends with <rhs>.

SELECT trim('ababccaab', 'ab') str;

+------+
| str  |
+------+
| cca  |
+------+

3. UTF-8 character support

SELECT trim('   ṭṛì ḍḍumai   ');

+------------------------------+
| trim('   ṭṛì ḍḍumai   ')     |
+------------------------------+
| ṭṛì ḍḍumai                   |
+------------------------------+

4. No matching prefix/suffix, return original string

SELECT trim('Hello World', 'xyz');

+--------------------------------+
| trim('Hello World', 'xyz')     |
+--------------------------------+
| Hello World                    |
+--------------------------------+

5. NULL value handling

SELECT trim(NULL), trim('Hello', NULL);

+------------+-----------------------+
| trim(NULL) | trim('Hello', NULL)   |
+------------+-----------------------+
| NULL       | NULL                  |
+------------+-----------------------+

6. Empty string handling

SELECT trim(''), trim('abc', '');

+----------+------------------+
| trim('') | trim('abc', '')  |
+----------+------------------+
|          | abc              |
+----------+------------------+

7. Repeated pattern removal from both ends

SELECT trim('abcabcabc', 'abc');

+------------------------------+
| trim('abcabcabc', 'abc')     |
+------------------------------+
|                              |
+------------------------------+

8. Asymmetric removal

SELECT trim('abcHelloabc', 'abc');

+--------------------------------+
| trim('abcHelloabc', 'abc')     |
+--------------------------------+
| Hello                          |
+--------------------------------+

9. UTF-8 string with a UTF-8 trim pattern — only the leading ṭṛì is stripped because the trailing end does not match the pattern (+++), so trim stops there.

SELECT trim('ṭṛì ḍḍumai+++', 'ṭṛì');

+--------------------------------------------+
| trim('ṭṛì ḍḍumai+++', 'ṭṛì')               |
+--------------------------------------------+
|  ḍḍumai+++                                 |
+--------------------------------------------+

Keywords

TRIM