VB.Net using & _ to carry to next line - vb.net

Question

Error Error 1 Operator '&' is not defined for types 'String' and 'System.Windows.Forms.TextBox'.
What is wrong with this????!??
SQL = "UPDATE ATG_PP_QTE_HEAD SET " & _
"PART = '" & txtPart.Text & "', " & _
"LOCATION = '" & txtLoc.Text & "', " & _
"DESCRIPTION = '" & txtDescription.Text & "', " & _
"CUSTOMER = '" & txtCustID.Text & "', " & _
"CONTACT_NAME = '" & txtContactName.Text & "', " & _
"CONTACT_PHONE = '" & txtPhone.Text & "', " & _
"CONTACT_EMAIL = '" & txtEmail.Text & "', " & _
"LEAD_TIME = '" & txtLead.Text & "', " & _
"SETUP = " & txtSetup.Text & ", " & _
"WEIGHTPP = " & txtPCWT.Text & ", " & _
"NOTES = '" & txtNotes.Text & "', " & _
"LAST_MODIFIED = '" & DateTime.Now & "', " & _
"LABOR_RATE = " & txtLabor.Text & ", " & _
"OVERHEAD = " & txtOH.Text & ", " & _
"GA = " & txtGA.Text & ", " & _
"SORT_CODE = '" & txtSortCode.Text & "', " & _
"REFERENCE = '" & txtReference.Text & "', " & _
"PL = '" & txtPL.Text & "', " & _
"CUST_DRAW_NO = '" & txtCustDraw.Text & "', " & _
"COMMISSION = " & txtCommission.Text & ", " & _
"PCWT = " & txtPCWT & _
"WHERE QUOTE_ID = " & txtQuoteID.Text

Answer 1

What is wrong with this????!??
Quite a bit, actually. But let's start with the error itself...
On this line:
"PCWT = " & txtPCWT & _
You're trying to concatenate a TextBox to a String. As the error states, you can't do that. Perhaps you meant to use the .Text property:
"PCWT = " & txtPCWT.Text & _
Now, what else is wrong?
First, your code is highly vulnerable to SQL injection attacks. You're going to want to use parameterized queries instead of executing user input as code.
Second, using parameterized queries will make the code a lot easier to read and support, which will make errors like this much easier to find.
Third, on this line there's a significant potential for bugs:
"LAST_MODIFIED = '" & DateTime.Now & "', " & _
Using parameterized queries will remove the culture-dependent string representations from the query and use the actual DateTime data in the query. And you should also get into the habit of using DateTime.UtcNow instead, as having a consistent non-timezone-dependent value is going to make things a lot easier when you have to deal with multiple time zones.