>
> I posted something like this a week ago, but typos in my message kept
> anyone from understanding the issue.
>
> I am trying to return each row to the client as it comes from the
> database, instead of waiting for all the rows to be returned before
> displaying them.
Why would you want to do this ?
Writing your application this way will ensure that:
a. end users can crash your server/application.
b. your application will preform poorly on the network.
Buffer your output, and when all the output is collected, print it, and
let tcp deliver the data in network-friendly chunks. If your database is
that slow that you think you need an approach like this, investigate the
possibility of a caching server process that you can sit in front of the
actual db.
You need to consider what happens when a user executes a query that can
return more rows that a browser can reasonably display. In other words,
having a query results pagination module or feature is probably a must.
If you were writing a stand-alone application that ran on a single cpu
(like MS Access on a local file) in this style (no pagination, no
buffering) I would consider this to be marginally bad style. Inside a
web-based application, this approach is horrendous.
Just my 2 cents . . .
On Sat, 23 Dec 2000, quagly wrote:
>
> I have set $|=1 and added $r->flush; after every print statement ( I
> realize this is redundant ) but to no avail.
>
> This is the relevant code:
>
> while ($sth->fetch) {
> $r->print ("<TR>",
> map("<TD>$_</TD>",@cols),
> "</TR>");
> $r->rflush;
> }
>
> Here is the complete package:
>
> package Sql::Client;
>
> use Apache::Request;
> use strict;
> use warnings;
> use Apache::Constants qw(:common);
>
> my $r; #request
> my $apr; #Apache::Request
> my $host; #hostname of remote user
> my $sql; #sql to execute
>
> $|=1;
>
> sub getarray ($) {
>
> my $dbh; # Database handle
> my $sth; # Statement handle
> my $p_sql; # sql statement passed as parameter
> my @cols; #column array to bind results
> my $titles; # array ref to column headers
>
> $p_sql = shift;
>
> # Connect
> $dbh = DBI->connect (
> "DBI:mysql:links_db::localhost",
> "nobody",
> "somebody",
> {
> PrintError => 1, # warn() on errors
> RaiseError => 0, # don't die on error
> AutoCommit => 1, # commit executes
> immediately
> }
> );
>
> # prepare statment
> $sth = $dbh->prepare($p_sql);
>
> $sth->execute;
>
> $titles = $sth->{NAME_uc};
> #--------------
> # for minimal memory use, do it this way
> @cols[0..$#$titles] = ();
> $sth->bind_columns(\(@cols));
> $r->print( "<TABLE BORDER>");
> $r->print ("<TR>",
> map("<TD>$_</TD>",@$titles),
> "</TR>");
> while ($sth->fetch) {
> $r->print ("<TR>",
> map("<TD>$_</TD>",@cols),
> "</TR>");
> $r->rflush;
> }
> $r->print ("</TABLE>");
> return;
> }
>
>
> sub handler {
> $r = shift;
> $apr = Apache::Request->new($r);
> $sql = $apr->param('sql') || 'SELECT';
> $sql='SELECT' if $apr->param('reset');
>
> $r->content_type( 'text/html' );
> $r->send_http_header;
> return OK if $r->header_only;
> $host = $r->get_remote_host;
> $r->print(<<HTMLEND);
> <HTML>
> <HEAD>
> <LINK REL="stylesheet" TYPE="text/css"
> HREF="/styles/lightstyle.css"
> >
> <TITLE>Hello $host</TITLE>
> <BODY>
> <H1>Sql Client</H1>
> <FORM METHOD="POST">
> <P>Enter your Select Statement:
> <BR>
> <TEXTAREA NAME="sql" ROWS=8 COLS=60 WRAP>$sql</TEXTAREA>
> <BR>
> <INPUT TYPE="SUBMIT" VALUE="Submit">
> <INPUT TYPE="SUBMIT" NAME="reset" VALUE="Reset">
> </FORM>
> HTMLEND
> $r->rflush;
> getarray($sql) unless $sql =~ /^SELECT$/;
>
> $r->print(<<HTMLEND);
> </BODY>
> </HTML>
> HTMLEND
> return OK;
> }
> 1;
>
