how to validation the text box value ,nt edit more than bind

Question

Hi

 

am read value from SQL table in one text box depend upon the username its value will be different.so if i trying to edit it nt allow me to enter more than the read value

.

 

ex:

 

user name:   A      B            C         D

amount:       700    600      200      750

 

i bind the value amount in the text box as per the user name,so if edit it,it not allow more than 700.  

 

how to do that? please tell me code .

 username: A

text box 1:    700  (EDIT)

 

by clicking Edit i Enter New value in the text box,So that Value s not more than 700,as per  fr B is not more than 600....

how to bind and edit ,store value in string and check the condition...

 

plz help me tell clear code