没有x和y轴的箭头
html代码:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>折线</title>
<script src="https://code.jquery.com/jquery-3.3.1.min.js"></script>
</head>
<body>
<div style="height: 300px;">
<canvas id="myCanvas"></canvas>
<canvas id="yuan"></canvas>
</div>
<script type="text/javascript">
$(document).ready(function(){
// 画个圆
var y=document.getElementById("yuan");
var yuan=y.getContext("2d");
// 折线图的x轴和y轴
yuan.beginPath();
yuan.lineWidth = "2";
yuan.strokeStyle = "black";
yuan.moveTo(0,0);
yuan.lineTo(0,150);
yuan.lineTo(620,150);
yuan.stroke();
yuan.beginPath();
yuan.lineWidth="2";
yuan.strokeStyle="crimson";
$.ajax({
type:"post",
url:"json.php",
dataType:"json",
async:false,
success:function(data){
// 获取总数值条数,下一步需要拟定为数据库前三十一条
var numdata = data.length;
// alert(numdata);
for(var i=0;i<numdata;i++){
var user=data[i];
// 价钱
var a=user.vprice;
// 日期
var c=user.timestame;
// 画折线
var x=(i+1)*20;
var y=150-a*20;
// 画个端点圆
yuan.arc(x,y,2,0,2*Math.PI);
yuan.stroke();
}
},
error:function(data){
console.log("错误");
}
});
});
</script>
</body>
</html>
php代码
<?php
require "php/conndb.php";
$sql = "SELECT * FROM vegetables";
$result = $conn->query($sql);
$arr = array();
// 输出每行数据
while($row = $result->fetch_assoc()) {
$count=count($row);//不能在循环语句中,由于每次删除row数组长度都减小
for($i=0;$i<$count;$i++){
unset($row[$i]);//删除冗余数据
}
array_push($arr,$row);
}
//print_r($arr);
echo json_encode($arr,JSON_UNESCAPED_UNICODE);//json编码
?>
数据表设计: