Password Validation that contains 1 character 1 digit and having length of 8 Character using Regular Expression

Hi All....
              I want to create strong password validation that contains atleast one character , one digit ,no any special character allowed and having length of 8 to 12 digits
               I have used this expression that allows me to use 8 to 12 character..
           [^\s]{8,12}
           But i want to add more above functionalities also..
                        Any body help me..I want answer as soon as possible
 Thanks And Regards
Kinjal(Sharma Infoway)
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