Sometimes fields of a record contain no data or a NULL.
A person may not have a phone number, or a member is registered with a title
and last name but no first name. HTML tables will not automatically give you an
empty cell to represent NULL data. Instead, many browsers will close up the
empty space by shifting cells to the left to fill the gap. For example the cell
that contains the Last Name gets shifted under the First Name heading, and all
the rest of the row is similarly thrown off and a hole is generated all the way
in the right column. Again, this is not a problem for all browsers, IE 4 and 5
heal this type of error well.
The shortest solution is to always concatenate an
before the data in your cells. This code will create a space before the data.
Even if there is no data, the non-breaking space will hold the cell open. For
example:
Response.Write "<TD> " &
oRSp("NameFirst") & "</TD>"
Although this trick solves the
missing cell problem, it generates no small amount of angst in students. In the
lines above we are using the ampersand for the same purpose, but in two
different types of syntax. The first ampersand is for HTML, it is telling the
browser to add in a non-breaking space after the <TD>.
The second ampersand is for VBScript, telling it to add another term (the data
in the NameFirst field) to its Response.Write
string.
The first ampersand must go to the page so the browser can
see it, therefore it must be within the double quotes. It will be printed on
the page by ASP, and then go out to the network. The browser will interpret
that into a non-breaking space and remove the
(also known as an entity name) from the user's view.
The second ampersand will be used by ASP to build the string
<TD> John</TD> for Response.Write to put on the page. As that string is built, ASP
removes the ampersand, it is never seen by HTML. That second ampersand must go
outside the double quotes. The third ampersand is of the same type as the
second.
This code can also be
re-arranged to put the after the data which will preserve left-aligned columns, as follows.
Response.Write "<TD>" & oRSp("NameFirst")
& " </TD>"
A less obtrusive
technique is to insert the non-breaking space only if there is no data, as
shown in the following code
If IsNull(oRSp("NameFirst"))
Then
Response.Write " "
Else
Respone.write oRSp("NameFirst")
End If
By default, when you open a simple recordset it is a forward
only cursor. That means for walking through the records you have just two
options:
MoveFirst
MoveNext
You can only go forward through the recordset. After you go through the
recordset once you must use rs.MoveFirst prior to being able to go through the recordset
again. There is frequently confusion from my students that you only get one
pass through the recordset. But as long as after each pass you do a Move.First,
you can pass through many times. But you can never back up through the records
or jump ahead over records.
The most basic technique for reading data from a database
can be accomplished in three lines, plus the lines to write the data to the
page. The first line, Dim, sets aside a variable name, the second, SET,
makes an instance of the recordset class, and the third uses the OPEN
method to fill the object with a recordset.
Once filled, we can move down through the records of the
recordset writing data to the page.
Writing to the page is frequently done within an HTML table, which requires
shifting back and forth between HTML tags and ASP-ADO data. When writing code
you must be careful of a few traps including collapsed HTML cells from missing
data.
Visual Basic Books 
