Wildcards in MySql's like statement: percent sign, underscore and escape

Wildcards in MySql's like statement: percent sign, underscore and escape

% represents any number of characters
Sql code www.2cto.com 
select * from user where username like '%huxiao';  
 
select * from user where username like 'huxiao% ';  
 
select * from user where username like '%huxia%'; _represents  

a character
Sql code 
select * from user where username like '_';  
 
select * from user where username like 'huxia_';  
 
select * from user where username like 'h_xiao';  

If I really want to check % or _, what should I do? Using escape, the % or _ after the escape character will not be used as a wildcard. Note that the % and _ without escape characters in front of them still function as wildcards.
Sql code 
select username from gg_user where username like '%xiao/_%' escape '/ ';  
 
select username from gg_user where username like '%xiao/%%'