update only the aphabhetic part while keeping the numeric part constant?

i have obtained the sub string too. But problem is updating the alpha part only n preserving the numeric part.

while updating only the "book" part should be changed.

like
"book-0001","book-0002"
after
update
"bok1-0001", "bok1-0002"
and the length for alpha part is constant in my case.
and the numerical part is auto incremented.

this data is fetched from datagridview of previous form. N values need to updated in another form.
update query should be run for all item containing "book".

here is snippet of the code to fectch the data from datagrid
SqlConnection cin = new SqlConnection(str);
cin.Open();
SqlCommand cmd = new SqlCommand("select code from book where ISBN='" + selectedrow + "'", cin); //code is "book-0001, book-0002"
// string codebook = cmd.ExecuteScalar().ToString();
SqlDataReader dr = cmd.ExecuteReader();


string codebook = "";
string rate = "";
while (dr.Read() && dr.HasRows)
{
codebook += dr["code"].ToString() + "\n";
}

string alphaedit = codebook.Substring(0, 8);
this.textBox_Bookcode.Text = alphaedit;
string numedit = codebook.Substring(9, 4);
this.textBox_numcode.Text = numedit;

now i updated the code(ie book-0001) as bookcodefull

string bookcodefull = textBox_Bookcode.Text + "-" + numedit;
// textbox_bookcode is textbox= where user input new name for update for cook


while doing so
my result was

"cook-0001"
"cook-0001"

but required is
"cook-0001"
"cook-0002"

thank you all for the replies.

Replace worked :)

get the string from right side 4 chars parse it to int and then cocatenate it with 4 chars and increment the parse int.


if u give some code then only we can give the required code or else we can just give u hint