Forget unclosed quotation mark, you will easily fix this problem if you re-write your code in accurate way.
Your approach is wrong from the very beginning. The query composed by concatenation with strings taken from UI. Not only repeated string concatenation is inefficient (because strings are
immutable; do I have to explain why it makes repeated concatenation bad?), but there is way more important issue: it opens the doors to a well-known exploit called
SQL injection.
This is how it works:
http://xkcd.com/327.
Are you getting the idea? The string taken from a control can be anything, including… a fragment of SQL code.
What to do? Just read about this problem and the main remedy:
parametrized statements:
http://en.wikipedia.org/wiki/SQL_injection.
With ADO.NET, use this:
http://msdn.microsoft.com/en-us/library/ff648339.aspx.
Please see my past answers for some more detail:
EROR IN UPATE in com.ExecuteNonQuery();,
hi name is not displaying in name?.
—SA