+-----------+-----------+------+-----+-------------------+-----------------------------+
| Field     | Type      | Null | Key | Default           | Extra                       |
+-----------+-----------+------+-----+-------------------+-----------------------------+
| EID       | int(11)   | NO   | PRI | 0                 |                             |
| MOD_EID   | int(11)   | YES  |     | NULL              |                             |
| EXIT_TIME | timestamp | NO   |     | CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP |
+-----------+-----------+------+-----+-------------------+-----------------------------+

String vexit=request.getParameter("string");

StringTokenizer tok=new StringTokenizer(vexit,"");

String sql,query,query2;
int count2=0;


    while(tok.hasMoreTokens())
    {
            String ide=tok.nextToken();
sql="SELECT count(EID) FROM tm_exit where EID='"+ide+"' ";
            ResultSet rs=st.executeQuery(sql);
            while(rs.next())
            {
            count2=rs.getInt(1);
}
        if(count2 >0)
            {
query="UPDATE tm_exit set MOD_EID='"+ide+"' WHERE EID='"+ide+"'";
int flag=st.executeUpdate(query);
}
        else
            {
query2="INSERT INTO tm_exit (EID,MOD_EID)values('"+ide+"',0)";
int flag2=st.executeUpdate(query2);
}
    }