php - JpGraph:使用 MySQL 数据创建 PHP 条形图

Question

通过取mysql数据库表的值，想用PHP制作一个条形图。我使用 JpGraph 绘制条形图。我想从“学生”表中获取数据。我有一个名为“类别”的列，其中的值是“全职”或“兼职”。我想数一数。类别为“全职”的行数和类别为“兼职”的行数。 x 轴应该是类别，y 轴应该是相关的行数。PHP代码如下；

<?php
 require_once('/jpgraph-3.5.0b1/src/jpgraph.php');
 require_once('/jpgraph-3.5.0b1/src/jpgraph_bar.php'); 
 $db = mysql_connect("localhost", "root","") or die(mysql_error());

 mysql_select_db("mphildatabase",$db) or die(mysql_error());

 $sql1 = mysql_query("SELECT category FROM student") or die(mysql_error());
 $sql2 = mysql_query("SELECT COUNT(*) FROM student WHERE category='Full Time'") or die(mysql_error());
 $sql3 = mysql_query("SELECT COUNT(*) FROM student WHERE category='Part Time'") or die(mysql_error());
 while($row1 = mysql_fetch_array($sql1))
 {
 $row2 = mysql_num_rows($sql2);
 $row3 = mysql_num_rows($sql3);
 $data[] = $row2;
 //$data[] = $row3;
 $leg[] = $row1['category'];
 }
 $graph = new Graph(950,750,"auto");
 $graph->SetScale("textint");
 $graph->img->SetMargin(50,30,50,50);

 $graph->SetShadow();

  $graph->xaxis->SetTickLabels($leg);

  $bplot = new BarPlot($data);
  $bplot->SetFillColor("lightgreen"); 
  $bplot->value->Show();
  $bplot->value->SetFont(FF_ARIAL,FS_BOLD);
  $bplot->value->SetAngle(45);
  $bplot->value->SetColor("black","navy");

  $graph->Add($bplot);
  $graph->Stroke(); ?>

这将为每一行提供单独的条形图。每行都会打印条形图，所有这些条形图的 y 轴值为 1。如何绘制只有 2 个条形图的条形图，一个显示类别为“全职”的行数和其他栏显示类别为“兼职”的行数？谢谢!

Answer 1

您必须只使用一个查询，并在一个循环中填充数组。您的查询必须是:

"SELECT count(*) as num_rows, category from 
student WHERE category ='Full Time' or Category= 'Part Time'
Group by Category
  "

...

while($row1 = mysql_fetch_array($sql1))
{
$leg[] = $row1['category'];
$data[] = $row1['num_rows']
}