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                |
+-------------+---------------------+