Texbox validation in datagrid

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Hello All,

I need some help. I have a dynamic grid and in that i have few
texboxes.One text box contain the serial number which is auto generated
and could be modified by the user. My requirement is the user should
not be able to enter a serial number which is already there in some
texbox. In the sense.

Suppose these are the values in the Textboxes
TB1: 1
TB2: 2
TB3: 3

Now the user should be able to enter any value other than 1 or 2 in
TB3.

Thanks in advance and please do let me know soon. Its urgent.

Thanks
Manish

[Thread]

How can i do it.

Regards
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