Re^4: Getting mysql data into gd

There are 4 or more rows of data

The query works

DEBUG:  $sth = "DBI::st=HASH(0x15e6e68)"
DEBUG:  @row = "07:40 62.50 64.00 69.40"
  [0] = "07:40"
  [1] = "62.50"
  [2] = "64.00"
  [3] = "69.40"
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We are getting only one row and the fallowing error.

Can't call method "add_point" on an undefined value at ./graph.cgi line 54.

Time is the x value and the numbers are the temp. I removed time from the query and it still fails.

Comment on Re^4: Getting mysql data into gd Download Code

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Re^5: Getting mysql data into gd by poj (Abbot) on Sep 03, 2017 at 19:28 UTC
Try #!/usr/bin/perl use strict; use DBI; use GD::Graph::Data; use GD::Graph::bars; my $batchnumber = '20170903nervana'; my $sql = ' SELECT time, mastuntemp, LineTemp, spargtemp FROM brew_temp_tb WHERE sitename = ? AND batchnumber = ? ORDER BY time'; my $dbh = dbh(); # connect my $sth = $dbh->prepare($sql); $sth->execute('Brew',$batchnumber); my $data = GD::Graph::Data->new(); while (my @row = $sth->fetchrow_array){ $data->add_point(@row); } my $chart = GD::Graph::bars->new(); my $gd = $chart->plot($data); open(IMG, '>','bar.png') or die $!; binmode IMG; print IMG $gd->png; # connect sub dbh{ my $database = "test"; my $user = "user"; my $pw = "password"; my $dsn = "dbi:mysql:$database:localhost:3306"; my $dbh = DBI->connect($dsn, $user, $pw, { RaiseError=>1, AutoCommit=>1 } ); return $dbh; } [download] poj	[reply] [d/l]

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Re^5: Getting mysql data into gd
by poj (Abbot) on Sep 03, 2017 at 19:28 UTC

Try

#!/usr/bin/perl
use strict;
use DBI;
use GD::Graph::Data;
use GD::Graph::bars;

my $batchnumber = '20170903nervana';

my $sql = '
  SELECT time, mastuntemp, LineTemp, spargtemp 
  FROM brew_temp_tb 
  WHERE sitename = ? 
    AND batchnumber = ?
  ORDER BY time';

my $dbh = dbh(); # connect
my $sth = $dbh->prepare($sql);
$sth->execute('Brew',$batchnumber);           
           
my $data = GD::Graph::Data->new();
while (my @row = $sth->fetchrow_array){
  $data->add_point(@row);
}

my $chart = GD::Graph::bars->new();
my $gd = $chart->plot($data);
open(IMG, '>','bar.png') or die $!;
binmode IMG;
print IMG $gd->png;

# connect
sub dbh{
  my $database = "test"; 
  my $user     = "user"; 
  my $pw       = "password";
  my $dsn = "dbi:mysql:$database:localhost:3306"; 
  my $dbh = DBI->connect($dsn, $user, $pw, 
     { RaiseError=>1, AutoCommit=>1 } );
  return $dbh;
}
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