Firstly you should be using a stored procedure to do this.
Here's a solution:
qry = "insert into wiki (column1, column2, column3, column4) values('" + file_name + "','" + file_size + "','" + file_url + "','" + file_category + "','" + file_view +"','"+ "')";
You need to specify the columns into which the data is going to go. Rename the columns to those that you are actually putting the data into.