MySQL clears the space at the beginning and end of a string.

The space function at the beginning and end of a string in MySQL is a frequently used function. The space function at the beginning and end of a string in MySQL contains three types: ltrim (), rtrim (), trim (), next we will introduce you separately.

 
 

  
  
mysql> select concat('.', ltrim(' ddd '), '.');  
  
  
+----------------------------------+  
  
  
| concat('.', ltrim(' ddd '), '.') |  
  
  
+----------------------------------+  
  
  
| .ddd .                           |  
  
  
+----------------------------------+  
  
  
mysql> select concat('.', rtrim(' ddd '), '.');  
  
  
+----------------------------------+  
  
  
| concat('.', rtrim(' ddd '), '.') |  
  
  
+----------------------------------+  
  
  
| . ddd.                           |  
  
  
+----------------------------------+  
  
  
mysql> select concat('.', trim(' ddd '), '.');  
  
  
+---------------------------------+  
  
  
| concat('.', trim(' ddd '), '.') |  
  
  
+---------------------------------+  
  
  
| .ddd.                           |  
  
  
+---------------------------------+ 
 
 

The trim string function in MySQL is really powerful. It not only removes spaces at the beginning and end of a string, but also removes any specified characters. Ltrim (), rtrim () is only a subset of its functions. Let's take a look at the complete syntax of the trim function:

1. trim ([{both | leading | trailing} [remstr] from] str)
2. trim ([remstr from] str)

1. Clear the first character of the string.

 
 

  
  
ysql> select trim(leading '.' from '..ddd..');  
  
  
+----------------------------------+  
  
  
| trim(leading '.' from '..ddd..') |  
  
  
+----------------------------------+  
  
  
| ddd..                            |  
  
  
+----------------------------------+ 
 
 

2. Clear the tail character of the string.

 
 

  
  
mysql> select trim(trailing '.' from '..ddd..');  
  
  
+-----------------------------------+  
  
  
| trim(trailing '.' from '..ddd..') |  
  
  
+-----------------------------------+  
  
  
| ..ddd                             |  
  
  
+-----------------------------------+ 
 
 

3. Clear the first and end characters of the string.

 
 

  
  
mysql> select trim(both '.' from '..ddd..');  
  
  
+-------------------------------+  
  
  
| trim(both '.' from '..ddd..') |  
  
  
+-------------------------------+  
  
  
| ddd                           |  
  
  
+-------------------------------+  
  
  
mysql> select trim('.' from '..ddd..');  
  
  
+--------------------------+  
  
  
| trim('.' from '..ddd..') |  
  
  
+--------------------------+  
  
  
| ddd                      |  
  
  
+--------------------------+ 
 
 

Trim () removes spaces at the beginning and end of the string by default.

The preceding sections describe the space function at the beginning and end of a string in MySQL.

MySQL string case-sensitive Conversion Function

Use of MySQL concat Functions

Obtain the Automatically increasing MySQL primary key

MySQL primary key design principles

MySQL partition functions and restrictions