0、引言
之前操作单表的增删改！可是当需要下拉框选择查询时需要用到下拉框的代码。
之后要求一个页面同时选择提交两个表单，再对其两个表单对应的数据进行加权计算
所以本文章包含的内容：
1、表单的查询
2、下拉框的查询
3、多表查询，并实现一个提交按钮同时提交查询
4、将查询的内容进行加法乘法计算
5、将计算的结果显示到对应的表单以便用户查看。
一、两个表单同时提交需要注意
1、两个表如果不一样可以分别，如果一样本人在数据库创建了两份，命名不一样。一个为meiyang，一个为meiyang1.
因为在查询时其主键id名字如果一样会产生覆盖的情况
所有两个表单数据结构完全一样，只有主键名字要不同，一个叫id，另一个叫ID。这样取出来就不会产生覆盖了。
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2、要想在查询后网页不刷新，要求点击提交按钮后表格内容还显示那个东西需要写如下代码
if(!empty($_POST['ID']))
{ echo $_POST['ID'];}
else{
echo "请选择媒样";
}这样在选择查询之后这个input显示的就是查询的内容。
二、本设计
1、样式
实现的功能就是选择两种煤种，然后配比，煤种1的数乘以配比的数，再加上煤种2的数乘以相应配比的数。
$res1['P2O5']*$n1+$res2['P2O5']*$n2
2、下拉框效果：
三、所有代码完整
<?php
include('conn.php');
?>
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>系统</title>
<link href="css/init.css" rel="stylesheet" />
<link href="css/mei_genxin.css" rel="stylesheet" />
<style type="text/css">
#saveHistory {behavior:url(#default#savehistory);}
</style>
</head>
<body>
<form action=" " method="post" name="form1" >
<div class="e1">
<h2>指标预测（二元）</h2>
</div>
<div class="e2">
<span class="style2">选择煤种1</span>
<select name="ID" >
<option>
<?php
if(!empty($_POST['ID']))
{ echo $_POST['ID'];}
else{
echo "请选择媒样";
}
?>
</option>
<?php
$sql1="select * from meiyang1 ";
$res1=mysqli_query($con,$sql1);
while($row1=$res1->fetch_assoc())
{
//var_dump($row);
?>
<option >
<?php echo $row1["ID"];?>
<?php echo $row1["CTYPE"];?>
</option>
<?php
}
?>
</select>
<!-- <input type="submit" class="button1" name="sub" value="开始搜索" /> -->
<span class="style2">选择煤种2</span>
<select name="id">
<option > <?php
if(!empty($_POST['id']))
{echo $_POST['id'];}
else{
echo "请选择媒样";
}
?>
</option>
<?php
$sql2="select * from meiyang ";
$res2=mysqli_query($con,$sql2);
while($row2=$res2->fetch_assoc())
{
//var_dump($row);
?>
<option>
<?php echo $row2["id"];?>
<?php echo $row2["CTYPE"];?>
</option>
<?php
}
?>
</select>
<span class="style2">配比设定</span>
<!-- <input type="text" style="width: 50px;height: 24px;border-radius: 2px;" name="n1" value="" /> -->
<input type="text" style="width: 50px;height: 24px;border-radius: 2px;" name="n1"
value="<?php if(!empty($_POST['n1'])){echo $_POST['n1'];} else{echo "0";}?>" />
:
<input type="text" style="width: 50px;height: 24px;border-radius: 2px;" name="n2"
value="<?php if(!empty($_POST['n2'])){echo $_POST['n2'];} else{echo "0";}?>" />
<input type="submit" class="button1" style="margin-left: 30px;" value="煤种配比" >
<input type="button" class="button1" style="margin-left: 30px;" value="基础性预测" >
<input type="button" class="button1" style="margin-left: 30px;" value="FT预测" name="" onclick="">
</div>
<div class="e2">
</div>
</form>
<?php
$id1 = $_POST["ID"];
if(!empty($_POST["n1"])){
$n1=$_POST["n1"];
}
//根据id查到当前要操作的数据
$sql1= "select * from meiyang1 where id = '$id1'";
//查询
$result1=$con->query($sql1);
//var_dump($result1);//dedao
//得到具体信息
$res1 = $result1->fetch_assoc();
$id2 = $_POST["id"];
// $n1=$_POST["n1"];
// $n1=$_POST["n2"];
if(!empty($_POST["n2"])){
$n2=$_POST["n2"];
}
//根据id查到当前要操作的数据
$sql2= "select * from meiyang where id = '$id2'";
//查询
$result2=$con->query($sql2);
// var_dump($result);//dedao
//得到具体信息
$res2 = $result2->fetch_assoc();
?>
<form action="" method="post" name="form2">
<div class="e3">
<div class="e3_1">
<input type="hidden" value="<?php echo $id1;?> " name="id" >
<input type="hidden" value="<?php echo $id2;?> " name="id" >
<div class="e3_10">
<p>工业分析</p>
</div>
<div class="e3_11">
<span class="style1">Mar</span>
<br />
<span class="style1">Mad</span>
<br />
<span class="style1">Aad</span>
<br />
<span class="style1">Vdaf</span>
<br />
<span class="style1">Fcad</span>
</div>
<div class="e3_12">
<input class="input1" type="text" value="<?php echo $res1['Mar']*$n1+$res2['Mar']*$n2;?> " name="Mar"/>
<br />
<input class="input1" type="text" value="<?php echo $res1['Mad']*$n1+$res2['Mad']*$n2;?> " name="Mad"/>
<br />
<input class="input1" type="text" value="<?php echo $res1['Aad']*$n1+$res2['Aad']*$n2;?> " name="Aad"/>
<br />
<input class="input1" type="text" value="<?php echo $res1['Vdaf']*$n1+$res2['Vdaf']*$n2;?> " name="Vdaf"/>
<br />
<input class="input1" type="text" value="<?php echo $res1['Fcad']*$n1+$res2['Fcad']*$n2;?> " name="Fcad"/>
</div>
</div>
<div class="e3_1">
<div class="e3_10">
<p>元素分析</p>
</div>
<div class="e3_11">
<span class="style1">Cad</span>
<br />
<span class="style1">Had</span>
<br />
<span class="style1">Nad</span>
<br />
<span class="style1">Oad</span>
<br />
<span class="style1">St_ad</span>
</div>
<div class="e3_12">
<input class="input1" type="text" value="<?php echo $res1['Cad']*$n1+$res2['Cad']*$n2;?> " name="Cad"/>
<br />
<input class="input1" type="text" value="<?php echo $res1['Had']*$n1+$res2['Had']*$n2;?> " name="Had"/>
<br />
<input class="input1" type="text" value="<?php echo $res1['Nad']*$n1+$res2['Had']*$n2;?> " name="Nad"/>
<br />
<input class="input1" type="text" value="<?php echo $res1['Oad']*$n1+$res2['Oad']*$n2;?> " name="Oad"/>
<br />
<input class="input1" type="text" value="<?php echo $res1['St_ad']*$n1+$res2['St_ad']*$n2;?> " name="St_ad"/>
</div>
</div>
<div class="" style="float: left;width:730px;height:240px; border: 3px #C0C0FF solid;border-right: none;">
<div class="e3_30">
<p>媒灰化学组成</p>
</div>
<div class="e3_31" style="float: left;margin-left: 10px;">
<br />
<span class="style1">SiO2 </span><input class="input1" type="text" value="<?php echo $res1['SiO2']*$n1+$res2['SiO2']*$n2;?> " name="SiO2"/>
<br />
<span class="style1">Al2O3 </span><input class="input1" type="text"value="<?php echo $res1['Al2O3']*$n1+$res2['Al2O3']*$n2;?> " name="Al2O3"/>
<br />
<span class="style1">Fe2O3</span><input class="input1" type="text" value="<?php echo $res1['Fe2O3']*$n1+$res2['Fe2O3']*$n2;?> " name="Fe2O3"/>
<br />
<span class="style1">MnO </span><input class="input1" type="text" value="<?php echo $res1['MnO']*$n1+$res2['MnO']*$n2;?> " name="MnO"/>
</div>
<div class="e3_31" style="float: left;margin-left: 10px;">
<br />
<span class="style1">CaO </span><input class="input1" type="text" value="<?php echo $res1['CaO']*$n1+$res2['CaO']*$n2;?> " name="CaO"/>
<br />
<span class="style1">MgO </span><input class="input1" type="text" value="<?php echo $res1['MgO']*$n1+$res2['MgO']*$n2;?> " name="MgO"/>
<br />
<span class="style1">K2O </span><input class="input1" type="text" value="<?php echo $res1['K2O']*$n1+$res2['K2O']*$n2;?> " name="K2O"/>
<br />
<span class="style1">Na2O </span><input class="input1" type="text" value="<?php echo $res1['Na2O']*$n1+$res2['Na2O']*$n2;?> " name="Na2O"/>
</div>
<div class="e3_31" style="float: left;margin-left: 10px;">
<br />
<span class="style1">P2O5 </span><input class="input1" type="text" value="<?php echo $res1['P2O5']*$n1+$res2['P2O5']*$n2;?> " name="P2O5"/>
<br />
<span class="style1">TiO2 </span><input class="input1" type="text" value="<?php echo $res1['TiO2']*$n1+$res2['TiO2']*$n2;?> " name="TiO2"/>
<br />
<span class="style1">SO3 </span><input class="input1" type="text" value="<?php echo $res1['SO3']*$n1+$res2['SO3']*$n2;?> " name="SO3"/>
<br />
<span class="style1">LOI </span><input class="input1" type="text" value="<?php echo $res1['LOI']*$n1+$res2['LOI']*$n2;?> " name="LOI"/>
</div>
</div>
</div>
<div class="e3">
<div class="e3_1">
<div class="e3_10">
<p>有害元素</p>
</div>
<div class="e3_11">
<span class="style1">Fad</span>
<br />
<span class="style1">Clad</span>
<br />
<span class="style1">Asad</span>
<br />
<span class="style1">Hgad</span>
</div>
<div class="e3_12">
<input class="input1" type="text" value="<?php echo $res1['Fad']*$n1+$res2['Fad']*$n2;?> " name="Fad"/>
<br />
<input class="input1" type="text" value="<?php echo $res1['Clad']*$n1+$res2['Clad']*$n2;?> " name="Clad"/>
<br />
<input class="input1" type="text" value="<?php echo $res1['Asad']*$n1+$res2['Asad']*$n2;?> " name="Asad"/>
<br />
<input class="input1" type="text" value="<?php echo $res1['Hgad']*$n1+$res2['Hgad']*$n2;?> " name="Hgad"/>
</div>
</div>
<div class="e3_1">
<div class="e3_10">
<p style="font-size: 18px;">FT熔温特性</p>
</div>
<br /><br />
<span class="style1" >FT指数 </span>
<input class="input1" type="text" style=";" value="<?php echo $res1['FT']*$n1+$res2['FT']*$n2;?> " name="FT"/>
<br /><br />
<span class="style1" >FT指数预测</span>
<input class="input1" type="text" value="" name="FTzsyc"/>
<br /><br /><br /><br />
</div>
<div class="e3_1">
<div class="e3_10">
<p>其他信息</p>
</div>
<div class="e3_11">
<span class="style1">Qnet</span>
<br/>
<span class="style1">Qbad</span>
<br/>
<span class="style1" >HGI</span>
<br/>
<span class="style1">JZTX</span>
</div>
<div class="e3_12">
<input class="input1" type="text" value="<?php echo $res1['Qnet']*$n1+$res2['Qnet']*$n2;?> " name="Qnet"/>
<br/>
<input class="input1" type="text" value="<?php echo $res1['Qbad']*$n1+$res2['Qbad']*$n2;?> " name="Qbad"/>
<br/>
<input class="input1" type="text" value="<?php echo $res1['HGI']*$n1+$res2['HGI']*$n2;?> " name="HGI"/>
<br/>
<input class="input1" type="text" value="<?php echo $res1['JZTX']*$n1+$res2['JZTX']*$n2;?> " name="JZTX"/>
</div>
</div>
<br /><br />
<input type="button" class="button2" name="insub" value="结渣特性预测"/>
<input type="button" class="button2" value="数据清除" onclick="alert('确认清除!')"/>
<br /><br />
<input type="button" name="insub" class="button2" value="粘温特性预测" />
<!-- <input type="button" class="button2" onclick="javascript : history.back();" value="返 回"/> -->
<a href="index.php">
<input type="button" class="button2" value="返回首页"/>
</a>
</div>
</form>
</body>
</html>代码分析：
整个可以分为两个form，第一个为form1提交表单，第二个form2为提交后的表单所写的位置，注意这里第二个可以不用表单，因为他不需要进行操作，本人设为表单就是为了后续的内容补充，对其数据进一步进行操作。
其中主要提交两个表单的功能代码在form1中。实现了两次查询，查询出来的数据放入不同命名的变量数组中。最后用一个提交按钮，就是submit。
整个代码看起来不复杂，但是本人也是研究了好久，为了实现同一页面提交两个表单，也是试了无数种方法。终于自学试出来了，想着纪念一下。