LTRIM

Description

The LTRIM function removes consecutive occurrences of spaces or specified character sets from the left side (beginning) of a string. This function scans from the left end of the string and removes all consecutive target characters until it encounters a character not in the target character set.

Syntax

LTRIM(<str> [, <trim_chars>])

Parameters

Parameter	Description
<str>	The source string to be left-trimmed. Type: VARCHAR
<trim_chars>	Optional parameter, specifies the set of characters to remove. If not provided, defaults to removing space characters. Type: VARCHAR

Return Value

Returns VARCHAR type, representing the string after removing specified characters from the left side.

Trimming rules:

• Only removes characters from the left side (beginning) of the string
• Removes all consecutive characters that appear in trim_chars
• Stops removing once a character not in trim_chars is encountered
• If trim_chars is not specified, defaults to removing space characters (including spaces, tabs, newlines, etc.)

Special cases:

• If any parameter is NULL, returns NULL
• If str is empty string, returns empty string
• If trim_chars is empty string, returns original string
• If entire string consists of characters in trim_chars, returns empty string

Examples

1. Remove left spaces

SELECT LTRIM('   ab d');

+-------------------+
| LTRIM('   ab d')  |
+-------------------+
| ab d              |
+-------------------+

2. Remove specified characters

SELECT LTRIM('ababccaab', 'ab');

+----------------------------+
| LTRIM('ababccaab', 'ab')   |
+----------------------------+
| ccaab                      |
+----------------------------+

3. NULL value handling

SELECT LTRIM(NULL), LTRIM('test', NULL);

+-------------+---------------------+
| LTRIM(NULL) | LTRIM('test', NULL) |
+-------------+---------------------+
| NULL        | NULL                |
+-------------+---------------------+

4. Empty inputs

SELECT LTRIM(''), LTRIM('test', '');

+-----------+-------------------+
| LTRIM('') | LTRIM('test', '') |
+-----------+-------------------+
|           | test              |
+-----------+-------------------+

5. Strip a multi-character prefix

SELECT LTRIM('abcdefg', 'abc'), LTRIM('123456', '12');

+-------------------------+-----------------------+
| LTRIM('abcdefg', 'abc') | LTRIM('123456', '12') |
+-------------------------+-----------------------+
| defg                    | 3456                  |
+-------------------------+-----------------------+

6. Entire string matches the trim chars

SELECT LTRIM('aaaaa', 'a'), LTRIM('   ', ' ');

+---------------------+-------------------+
| LTRIM('aaaaa', 'a') | LTRIM('   ', ' ') |
+---------------------+-------------------+
|                     |                   |
+---------------------+-------------------+

7. UTF-8 substring strip (the second arg is matched as a literal substring, not a character set)

SELECT LTRIM('ṭṛìṭṛì test', 'ṭṛì'), LTRIM('ḍḍuḍḍu hello', 'ḍu');

+--------------------------------------------+---------------------------------------+
| LTRIM('ṭṛìṭṛì test', 'ṭṛì')                | LTRIM('ḍḍuḍḍu hello', 'ḍu')           |
+--------------------------------------------+---------------------------------------+
|  test                                      | ḍḍuḍḍu hello                          |
+--------------------------------------------+---------------------------------------+

8. Strip a numeric prefix

SELECT LTRIM('000123', '0'), LTRIM('123abc123', '123');

+----------------------+---------------------------+
| LTRIM('000123', '0') | LTRIM('123abc123', '123') |
+----------------------+---------------------------+
| 123                  | abc123                    |
+----------------------+---------------------------+

9. Strip a punctuation prefix

SELECT LTRIM('---text---', '-'), LTRIM('@@hello@@', '@');

+--------------------------+-------------------------+
| LTRIM('---text---', '-') | LTRIM('@@hello@@', '@') |
+--------------------------+-------------------------+
| text---                  | hello@@                 |
+--------------------------+-------------------------+