Case-sensitive conversion in MySQL strings

The following articles mainly describe the practical application of MySQL strings, including case-sensitive conversion of MySQL database strings and how to clear spaces at the beginning and end of a string, the following is a detailed description. I hope you will get something.

MySQL string case-sensitive Conversion

DeMySQL string case-sensitive conversion functions include lower (), uppper (), lcase (), and ucase ()

 
 

  
  
mysql> select lower('DDD');
  
  
+--------------+| lower('DDD') |+--------------+|   
  
  
ddd |+--------------+mysql> select upper('ddd');  
  
  
+--------------+| upper('ddd') |+--------------+| DDD |+--------------+mysql> select lcase('DDD');  
  
  
+--------------+| lcase('DDD') |+--------------+| ddd |+--------------+mysql> select ucase('ddd');
  
  
+--------------+| ucase('ddd') |+--------------+| DDD |+--------------+ 
 
 

In general, I select lower () and upper () to convert string case, because it is compatible with functions in other databases.

Removes spaces at the beginning and end of a string.

In MySQL, there are three spaces at the beginning and end of the MySQL string: ltrim (), rtrim (), trim ()

 
 

  
  
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 MySQL string header characters.

 
 

  
  
mysql> 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() 
 
 

By default, spaces at the beginning and end of the MySQL string are cleared.