Building Tables with Data - Page 7
November 27, 2000
Very frequently your client will want to place data into an HTML
table, for display of the browser. To review some HTML, let me
state the three basic rules of table tags:
- Begin and end the entire table with
<TABLE
BORDER="1"> and </TABLE>
- Begin and end each row with
<TR> and
</TR>
- Begin and end each cell with
<TD> and
</TD>
Using the double quotes for the border value ensures universal
readability. However, many common browsers do not require them.
To build tables that display our data, we need to mix HTML table
tags into the data that ADO returns. The most basic table
contains only one row (one record or one name) and two columns,
as follows. This is artificially easy, but a good way to start:
<%
dim oRSst
Set oRSst=server.createobject("ADODB.recordset")
oRSst.open "People", "DSN=Sailors"
response.write "<table BORDER='1'>"
response.write "<tr>"
response.write "<td>"
response.write oRSst("PeopleNameFirst")
response.write "</td>"
response.write "<td>"
response.write oRSst("PeopleNameLast")
response.write "</td>"
response.write "</tr>"
response.write "</table>"
%>
The code sample above lays out the logic very explicitly. In the
following listing we condense this to fewer lines of code. Keep
in mind that this is still the same very simple 1-row, 2-column
table:
<%
dim oRSst2
Set oRSst2=server.CreateObject("ADODB.recordset")
oRSst2.open "People", "DSN=Sailors"
Response.Write "<TABLE BORDER='1'><TR><TD>"
Response.Write oRSst2("PeopleNameFirst")
Response.Write "</TD><TD>"
Response.Write oRSst2("PeopleNameLast")
Response.Write "</TD></TR></TABLE>"
%>
We can also use the Response.Write shortcut to further condense
the code that generates this table, as follows. However, it is
general good practice not to code your ASPs this way as
separating your server side scripting rather than keeping it all
together in the same place degrades performance.
<%
dim oRSst3
Set oRSst3=server.CreateObject("ADODB.recordset")
oRSst3.open "People", "DSN=Sailors"
%>
<TABLE BORDER="1">
<TR><TD><%=oRSst3("PeopleNameFirst")%></TD>
<TD><%=oRSst3("PeopleNameLast")%></TD></TR>
</TABLE>
Building Tables with For...Next Loops
It is rare that you have a client that will be satisfied with a
one-row table! Tables usually present data on many records. We
will explore that technique first with a table that produces
three rows as a result of putting the code for a row within a
For...Next loop in the code below. Of course, we can only loop
within ASP, so we will have to forget about the
Response.Write shortcut used above; instead we'll
revert to writing the HTML tags from within ASP, and using
Response.Write explicitly:
<%
dim iRowCounter
dim oRSfn
set oRSfn=server.CreateObject("adodb.recordset")
oRSfn.open "People", "DSN=Sailors"
oRSfn.MoveFirst
Response.Write "<TABLE BORDER='1'>"
For iRowCounter=1 to 3
Response.Write "<TR><TD>" & oRSfn("PeopleNameFirst") & "</TD>"
Response.Write "<TD>" & oRSfn("PeopleNameLast") & "</TD></TR>"
oRSfn.MoveNext
Next
Response.Write "</TABLE>"
%>
Note in the above listing that we have to be sure that the table
tags are outside of the loop but the rows and cell tags are
inside the loop. For the purposes of this demo we are assuming
that there are at least three records; in the real world that
would be a dangerous assumption.
The common errors on the above code include:
- (the usual problems in creating recordsets)
- Putting the
<TABLE> or
</TABLE> inside the loop
- Leaving out
</TABLE>
- Putting more than one
<TR> or </TR> in a row
- Forgetting to include the
.MoveNext line within the loop
- Trying to retrieve more records than are available in the database
In later sections of the book we discuss even faster and more
eloquent ways to build a table.
Which Record? - Page 6
Beginning ASP Databases
Building a Table - Page 8
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