mysql character classes and repeating metacharacter

 

Character class 

[: alnum:] = [A-zA-Z0- . 9 ] 

[: Alpha:] = [A-ZA- the Z] 

[: digit for:] = [ 0 - . 9 ] 

[: Lower:] = [A- Z] 

[: Upper:] = [A- the Z] 

[: xdigit:] = [fA-A-F0- . 9 ] 



repeating metacharacter

 * => = 0 
+ => = 1 = { 1 }
 = {? 0 , . 1 } 

{} n-specified number 
{n-,} => = n- 
{n-, m} => = n-and <= m