Jan-Willem

Several tags have not been closed; the meta's, the link's; later on there's several </br> that should be <br />. A few other erors as well (missing </article>. xhtml is a lot more picky than html...

This text "SELECT TXT" + "FROM (...)" will resolve to SELECT TXTFROM (...)" As a result of that the FROM keyword will not be found Should read "SELECT TXT " + "FROM (...) " I prefer to add a space to all substrings that are part of a SQL statement.

Does the parent class have a method protected virtual void onload(EventArgs e) { //... } ?

also, there's a comma before WHERE

Can you be sure a record will be found to update, given the test WHERE BlockNo='" + BlockNo + "'" and the fact that BlockNo is allowed to be an empty string? Why the test if (BlockNo == "") if the code in both blocks is practically identical?

Starting with Firstname you code misses the closing-squotes: ", Firstname='" + Firstname + ", Familyname='" should read ", Firstname='" + Firstname + "', Familyname='"