快速编辑：虽然它说的是MAMP，但我只是将我的web项目存储在那里而我没有使用它提供的mysql服务器（虽然当我尝试它时抛出相同的错误），我使用MySQL workbench *附带的mysql
在我正在处理的PHP代码中，我按如下方式连接到我的数据库：
*{
margin: 0;
}
html {
position: relative;
min-height: 100%;
}
body {
background: #232526;
background: -webkit-linear-gradient(to right, #232526 , #414345);
background: linear-gradient(to right, #232526 , #414345);
margin: 0em;
font-family: 'Titillium Web', sans-serif;
font-size: 12px;
}
img{
width: auto;
height: 100%;
}
footer{
position: fixed;
margin: 0;
padding: 0;
bottom: 0;
width: 100%;
background-color: rgba(128,128,128,.3);
text-align: center; /*centers all of cooter */
max-height: 155px;
border-top: 1px solid #232526;
}
.left, .right{
display: inline-block;
list-style-type: none;
width: auto;
font-size: 100%;
vertical-align: top;
}
.left li{
text-align: right; /*aligns right within center */
color: rgb(192,192,192);
text-decoration: none;
}
.right li{
text-align: left;
}
footer ul.right li a{
text-decoration: none;
color: rgb(192,192,192);
}
.material-icons.md-14{
font-size: 1.167em;
}
.sliding-middle-out {
display: inline-block;
}
.sliding-middle-out:after {
content: '';
display: block;
margin: auto;
height: 0.167em;
width: 0;
background: transparent;
transition: width .5s ease, background-color .5s ease;
}
.sliding-middle-out:hover:after {
width: 100%;
}
ul.topnav {
margin: 0;
padding: 0;
overflow: hidden;
background-color: rgba(128,128,128,.3);
display: inline-block;
text-align: center;
width: 100%;
position: fixed;
border-bottom: 1px solid #232526;
}
ul.topnav li{
display: inline-block;
text-align: center;
}
ul.topnav li a {
color: rgb(192,192,192);
padding: 1.167em 1.333em;
text-decoration: none;
}
ul.topnav li a:hover {background-color: #232526;}
ul.topnav li a.active {background-color: rgba(228,230,229,.3);}
ul.topnav li.icon {display: none;}
a.navbar-brand{
text-decoration: none;
color: #666666;
}
.imgcont{
height: auto;
max-width: 100%;
margin: 0;
padding: 4.167em 0 0 0;
text-align: center;
}
ul.imgcont li{
display: inline-block;
width: auto;
}
ul.imgcont li a:hover {
background-color: rgba(200,200,200,.1);
border: 0.083em solid rgba(0,0,0,.5);
border-radius: 5px;
}
.text_box{
display: inline-block;
text-align: left;
vertical-align: top;
font-size: 28px;
color: rgb(192,192,192);
transform: translateY(150%);
}
@media screen and (max-width:760px) {
ul.topnav li:not(:first-child) {display: none;} /* makes navbar disapearr */
ul.topnav li.icon { /* creates the block for the toggle */
float: right;
display: inline-block;
}
ul.topnav.responsive {position: relative;}
ul.topnav.responsive li.icon {
position: absolute;
right: 0;
top: 0;
}
ul.topnav.responsive li {
float: none;
display: inline;
}
ul.topnav.responsive li a {
display: block;
text-align: left;
}
}
@media screen and (max-width:1216px) { /* These are here to fix the overlap issue */
ul.imgcont{
margin: 0;
padding: 4.167em 0 12.500em 0;
}
}
@media screen and (max-width:1083px) {
ul.imgcont{
margin: 0;
padding: 8.333em 0 12.500em 0;
}
}
@media screen and (max-width:897px) {
.text_box{
transform: translateY(0%);
}
}
@media screen and (max-width:760px) {
ul.imgcont{
margin: 0;
padding: 4.167em 0 170px 0;
}
}
@media screen and (max-width:755px) {
ul.imgcont{
margin: 0;
padding: 4.167em 0 12.500em 0;
}
.hidden-xs {
display: none !important;
}
}
#home.sliding-middle-out:hover:after {
background-color:grey;
}
#homer.sliding-middle-out:hover:after {
background-color:black;
}
#warrior.sliding-middle-out:hover:after {
background-color:#C79C6E;
}
#druid.sliding-middle-out:hover:after {
background-color:#FF7D0A;
}
#priest.sliding-middle-out:hover:after {
background-color:#FFFFFF;
}
#paladin.sliding-middle-out:hover:after {
background-color:#F58CBA;
}
#hunter.sliding-middle-out:hover:after {
background-color:darkgreen;
}
#mage.sliding-middle-out:hover:after {
background-color:#69CCF0 ;
}
#shaman.sliding-middle-out:hover:after {
background-color:#0070DE;
}
#warlock.sliding-middle-out:hover:after {
background-color:#9482C9;
}
#rogue.sliding-middle-out:hover:after {
background-color:#FFF569;
}
#minions.sliding-middle-out:hover:after {
background-color:#C41F3B;
}
#spells.sliding-middle-out:hover:after {
background-color:#A330C9;
}
#home.sliding-middle-out:hover:after {
background-color:black;
}
#warrior.sliding-middle-out:hover:after {
background-color:#C79C6E;
}
#druid.sliding-middle-out:hover:after {
background-color:#FF7D0A;
}
#priest.sliding-middle-out:hover:after {
background-color:#FFFFFF;
}
#paladin.sliding-middle-out:hover:after {
background-color:#F58CBA;
}
#hunter.sliding-middle-out:hover:after {
background-color:#ABD473
}
#mage.sliding-middle-out:hover:after {
background-color:#69CCF0 ;
}
#shaman.sliding-middle-out:hover:after {
background-color:#0070DE;
}
#warlock.sliding-middle-out:hover:after {
background-color:#9482C9;
}
#rogue.sliding-middle-out:hover:after {
background-color:#FFF569;
}
#minions.sliding-middle-out:hover:after {
background-color:#C41F3B;
}
#spells.sliding-middle-out:hover:after {
background-color:#A330C9;
}
#footer_MSoG.sliding-middle-out:hover:after {
background-color:black;
}
#footer_ONiK.sliding-middle-out:hover:after {
background-color:black;
}
#footer_WotOG.sliding-middle-out:hover:after {
background-color:black;
}
#footer_TLoE.sliding-middle-out:hover:after {
background-color:black;
}
#footer_TGT.sliding-middle-out:hover:after {
background-color:black;
}
#footer_BrM.sliding-middle-out:hover:after {
background-color:black;
}
现在，我通过我的终端（连接成功）测试了数据库的用户和密码，以及我的IDE（phpStorm）提供的也成功连接的接口。
我的问题如下：如何解决以下错误：
致命错误：未捕获错误：在/Applications/MAMP/htdocs/GIS/4Musketeers/PHP/common.php:20中调用null上的成员函数query（）
现在我知道它提到第20行，它引用了我的foreach块的开始：
" href="https://fonts.googleapis.com/icon?family=Material+Icons">
<link rel="stylesheet" href="https://fonts.googleapis.com/css?family=Titillium+Web">
<link rel="stylesheet" type="text/css" href="../../../Cardspoiler.css">
<ul class="topnav" id="myTopnav">
<li><a id="homer" class="sliding-middle-out" href="../../Navbar/Home.html">Cardspoiler</a></li>
<li><a id="home" class="sliding-middle-out" href="Home.html"><i class="material-icons md-14">home</i>Home</a></li> <!-- using the googleapis.com stylesheet -->
<li><a id="warrior" class="sliding-middle-out" href="Warrior.html"><i class="material-icons md-14">usb</i>Warrior</a></li>
<li><a id="druid" class="sliding-middle-out" href="Druid.html"><i class="material-icons md-14">brightness_high</i>Druid</a></li>
<li><a id="priest" class="sliding-middle-out" href="Priest.html"><i class="material-icons md-14">add_circle</i>Priest</a></li>
<li><a id="paladin" class="sliding-middle-out" href="Paladin.html"><i class="material-icons md-14">star_half</i>Paladin</a></li>
<li><a id="hunter" class="sliding-middle-out" href="Hunter.html"><i class="material-icons md-14">my_location</i>Hunter</a></li>
<li><a id="mage" class="sliding-middle-out" href="Mage.html"><i class="material-icons md-14">whatshot</i>Mage</a></li>
<li><a id="shaman" class="sliding-middle-out" href="Shaman.html"><i class="material-icons md-14">opacity</i>Shaman</a></li>
<li><a id="warlock" class="sliding-middle-out" href="Warlock.html"><i class="material-icons md-14">person_outline</i>Warlock</a></li>
<li><a id="rogue" class="sliding-middle-out active" href="Rogue.html"><i class="material-icons md-14">visibility_off</i>Rogue</a></li>
<li><a id="minions" class="sliding-middle-out" href="Minions.html"><i class="material-icons md-14">keyboard_arrow_up</i>Minions</a></li>
<li><a id="spells" class="sliding-middle-out" href="Spells.html"><i class="material-icons md-14">keyboard_arrow_down</i>Spells</a></li>
<li class="icon">
<a href="javascript:void(0);" style="font-size:30px;" onclick="myFunction()">☰</a>
</li>
</ul>
<div class="imgcont">
<img src="Counterfeit_Coin_I.png" alt="Counterfeit Coin"></a>
<div class="text_box">
Counterfeit Coin <br> Cost: 0 <br> Type: Spell <br> Text: Gain 1 Mana Crystal this turn only.
</div>
</div>
<footer>
<ul class="left hidden-xs">
<li>CARDSPOILER.COM <br> Freedom to know <br> We are here to bring you visual, leaked spoilers for all of the <br> cards you love within a simple gallery setting.</li>
<li><a href="mailto:help@cardspoiler.com" style="text-decoration:none;color:#9B764C;font-size: 10px;">CONTACT US</a>
<a href="../../Privacy_Policy.html" style="text-decoration:none;color:#9B764C;font-size: 10px;">PRIVACY POLICY</a></li>
</ul>
<ul class="right">
<li><a id="footer_MSoG" class="sliding-middle-out" href="MSoG.html">Mean Streets of Gadgetzan</a></li>
<li><a id="footer_ONiK" class="sliding-middle-out" href="ONiK.html">One Night in Karazhan</a></li>
<li><a id="footer_WotOG" class="sliding-middle-out" href="WotOG.html">Whispers of the Old Gods</a></li>
<li><a id="footer_TLoE" class="sliding-middle-out" href="tLoE.html">The League of Explorers</a></li>
<li><a id="footer_TGT" class="sliding-middle-out" href="TGT.html">The Grand Tournament</a></li>
<li><a id="footer_BrM" class="sliding-middle-out" href="BrM.html">Blackrock Mountain</a></li>
</ul>
</footer>
<script src="../../../Cardspoiler.js"></script>
我非常确信查询是正确的，因为它确实为我提供了我感兴趣的结果。查询是：
$dbh = new PDO('mysql:host=localhost:3306;dbname=mydb', $user, $pass);
结果是：
function printDirectors($sqlQuery) {
$index = 0; //Counting index for our table
global $dbh; //this is how we refer to our global $dbh up top.
foreach ($dbh->query($sqlQuery) as $result) {
echo "<tr><td class=\"index\">";
echo $index + 1 ."</td>";
echo "<td class=\"FirstName\">";
echo $result['first_name'] ."</td>";
echo "<td class=\"LastName\">";
echo $result['last_name'];
echo "</td></tr>";
$index++;
}
}
这是我第一次真正使用PDO或SQL与PHP，所以任何建议都将受到高度赞赏。
答案 0 :(得分：1)
正如输出所述，你得到这个的原因是因为你从未实例化$dbh。 PHP尝试在其上调用query方法，但它为空。