MySQL文字列の前後または中央の文字列を削除

1、replace関数
構文:replace(object,search,replace)の意味:objectに現れるsearchのすべてをreplaceに置き換える

select replace('    ',' ','');
+---------------------------+  
| replace('    ',' ','')   |  
+---------------------------+ 
|                          |  
+---------------------------+ 

--  table  name         
update table set name=replace(name,' ','') 

2、trim関数
構文:trim([{BOTH|LEADING|TRAILING}[remstr]FROM]str)意味:文字列の前または後に指定された文字列を削除する

--1、          
SELECT TRIM(' zhangsan  ');
+---------------------------+  
| TRIM(' zhangsan  ')       |  
+---------------------------+ 
| zhangsan                  |  
+---------------------------+ 
--2、          
SELECT TRIM(LEADING 'x' FROM 'xxxzhangsanxxx');
+------------------------------------------------+  
| TRIM(LEADING 'x' FROM 'xxxzhangsanxxx')        |  
+------------------------------------------------+ 
| zhangsanxxx                                    |  
+------------------------------------------------+ 
--3、          
SELECT TRIM(TRAILING 'x' FROM 'xxxzhangsanxxx');
+------------------------------------------------+  
| TRIM(TRAILING 'x' FROM 'xxxzhangsanxxx')       |  
+------------------------------------------------+ 
| xxxzhangsan                                    |  
+------------------------------------------------+ 
--4、          
SELECT TRIM(BOTH 'x' FROM 'xxxzhangsanxxx');
+------------------------------------------------+  
| TRIM(BOTH 'x' FROM 'xxxzhangsanxxx')           |  
+------------------------------------------------+ 
| zhangsan                                       |  
+------------------------------------------------+