Date changes to a vastly different value when saved into database - asp.net

Question

I'm trying to enter a date that's in a textbox into a column of datetime type
The code is as follows
txtbookissue_date.Text = DateTime.Now.Date
txtbookreturn_date.Text = DateAdd(DateInterval.Day, 7, DateTime.Now.Date)
When I Insert these two values into a database, (insert into book....) values such as 17-02-1984 show up in the database rather than, say, 26-2-2015.
I did a little research and found out that SQL interprets it as "26 minus 2 minus 2015" rather than as a date.
Printing Date(txtbookissue_date.Text) gives correct results, the only problem is saving it into the database.
The solution for this was apparently to enclose the date in single quotes, i.e '26-2-2015' rather than just 26-2-2015, Since I'm using a date function I decided to change
txtbookissue_date.Text = DateTime.Now.Date
to
txtbookissue_date.Text= "'"+DateTime.Now.Date+"'"
but It returns an error, something similar to 'cannot convert varchar type to date type, out of range exception'
How do I fix this? any help would be appreciated.
txtbookissue_date.Text = DateTime.Now.Date
txtbookreturn_date.Text = DateAdd(DateInterval.Day, 10, DateTime.Now.Date)
Protected Sub btn_issue_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btn_issue.Click
con.Open()
cmd.CommandText = "insert into Book (book_id, book_name, book_author,publisher,mem_id,mem_name,issue_date,return_date) values('" & txtbookissue_id.Text & "','" & txtibookssue_name.Text & "','" & txtbookissue_author.Text & "','" & txtbookissue_publi.Text & "','" & txtbookissue_memid.Text & "','" & txtbookissue_memname.Text & "'," & txtbookissue_date.Text & "," & txtbookreturn_date.Text & ")"
cmd.Connection = con
cmd.ExecuteNonQuery()
con.Close()
Response.Redirect("Welcome.aspx")
End Sub

Answer 1

you are inserting date as a text. I mean while you need to insert it '2015-02-26' you are trying to insert it with another format. In fact you should use parameters with your sql query. Your sql statement should be something like that
insert into Book (book_id, book_name, book_author,publisher,mem_id,mem_name,issue_date,return_date) values(#book_id, #book_name, #book_author,#publisher,#mem_id,#mem_name,#issue_date,#return_date)
Before executing query you should set parameters in command object.
cmd.Parameters.AddWithValue("#return_date", DateAdd(DateInterval.Day, 10, Date.Now.Date))
For more information about using parameters with access you can take a look here

Answer 2

First of all, I would highly suggest using Paramaters.
Second, since you want to format your date into a string that is not the default culture. I would suggest you use String.Format() or ToString() (examples).
Since your database most likely expects a datetime. You could parse the string back to a DateTime using DateTime.ParseExact. Look at this answer for a howto.
Let me know if this helps, if not you need to supply us with more info.

Answer 3

You are putting string in a DateTime column, please convert the values back to their original types before putting them in the database.
DateTime issueDate = DateTime.Parse(txtbookissue_date.Text);
DateTime returnDate = DateTime.Parse(txtbookreturn_date.Text);