在php文件的头部使用了namespace 结果报错mysqli不在LearningPHP1中,
结论：如果定义了命名空间，在使用mysqli做连接的时候就要指明mysqli所在的命名空间。
<?php//localhost/app/php/index.phpecho "IE快捷键 Ctrl+Tab下一标签页 Ctrl+Shift+Tab前一标签页<br/>";// 1.变量的声明echo "<h2>1.变量的声明</h2>";//$x=5; $y=6; $z=$x+$y; echo $z;//2.变量作用域echo "<h2>2.变量作用域</h2>";$x2= 5;function myTest(){//访问全局变量$x需要加上global关键字//也可以这样访问$x : $GLOBALS['x']global $x2;$y=10;echo "<p>测试函数内变量</p>";echo "变量x2为:$x2";echo "<br/>";echo "变量y为:$y<br/>";}myTest();//3.当一个函数运行结束时，内部变量都会被删除，通过static关键字可以不删除echo "<h2>3.static关键字</h2>";function test2(){static $x1 = 0;echo "static x1: $x1<br/>";$x1++;}test2();test2();test2();//4.参数传递echo "<h2>4.参数传递</h2>";$x41 = "郑文强";function myTest3($x41){echo "传入的是:$x41".'<br/>';echo '函数名为:'. __FUNCTION__ ;}myTest3($x41);//5. echo/printecho "<h2>5.echo/print</h2>";/*echo - 可以输出一个或多个字符串print - 只允许输出一个字符串，返回值总为 1echo 是一个语言结构，使用的时候可以不用加括号，也可以加上括号：echo 或 echo()。*/echo "I'm about to learn PHP!<br/>";echo "This ","String ","was ","made ","with multiple parameters.<br/>";$txt1="Learn PHP";$txt2="w3cschool.cc";$cars=array("Volvso","BMW","Toyota");echo $txt1,"<br/>";echo "Study PHP at $txt2<br/>";echo "My car is a $cars[0]";//6.数据类型echo "<h3>6.数据类型--整型</h3>";$x61 = 5985;var_dump($x61);echo "<br>";$x62 = -345; // 负数var_dump($x62);echo "<br>";$x63 = 0x8C; // 十六进制数var_dump($x63);echo "<br>";$x64 = 047; // 八进制数var_dump($x64);echo "<h3>数据类型--浮点型</h3>";$x65= 10.365;var_dump($x65);echo "<br>";$x66 = 2.4e3;var_dump($x66);echo "<br>";$x67 = 8E-5;var_dump($x67);echo "<h3>数据类型--数组</h3>";$cars=array("Volvo","BMW","Toyota");var_dump($cars);echo "<h3>数据类型--对象</h3>";class House{var $color;function House($color="green"){$this->color = $color;}function what_color(){return $this->color;}}echo "<h3>数据类型--常量 ,第三个参数默认为false,即区分大小写,这里设为true 不区分大小写</h3>";define("GREETING","欢迎访问 xxoo.com",true);echo GREETING,"<br/>";echo greeting;//7.字符串echo "<h2>7.字符串 并置运算符</h2>";$txt71="Hello Beijing ";$txt72="What A Nice Day";$txt73 = $txt71.$txt72;echo $txt73;/*strlen($txt73); 字符串长度strpos()函数用于在字符串内查找一个字符或一段指定的文本。如果在字符串中找到匹配，该函数会返回第一个匹配的字符位置。如果未找到匹配，则返回 FALSE*///8.运算符echo "<h2>8.运算符</h2>";echo "<h3>取模运算符</h3>";$x81=10; $y81=6;echo ( $x81 % $y81 );echo "<h3>三元运算符</h3>";$test81 = '菜鸟教程';$username = isset($test81)?$test81:'nobody';echo $username,PHP_EOL;//9.判断IF语句echo "<h2>9.判断IF语句</h2>";//判断当前时刻$h91=date("H");if($h91<16){echo "Have A Good Day!";}else{echo "Have A Good Night!";}//10.Switch 语句echo "<h2>10.Switch语句</h2>";$favcolor10="blue";switch ($favcolor10){case "red":echo "你喜欢的颜色是红色!";break;case "blue":echo "你喜欢的颜色是蓝色!";break;case "green":echo "你喜欢的颜色是绿色!";break;default:echo "你喜欢的颜色不是 红, 蓝, 或绿色!";}//11.数组echo "<h2>11.数组</h2>";$cars11=array("Volvo","BMW","Toyota");echo "I like " . $cars11[0] . ", " . $cars11[1] . " and " . $cars11[2] . ".<br/>";$arrlength=count($cars11);for($x=0;$x<$arrlength;$x++){echo $cars[$x];echo "<br>";}$age11=array("Peter"=>"35","Ben"=>"37","Joe"=>"43");echo "Peter is " . $age11['Peter'] . " years old.";//遍历关联数组foreach($age11 as $x=>$x_value){echo "Key=" . $x . ", Value=" . $x_value;echo "<br>";}//12.魔术常量echo '该文件位于 " ' . __FILE__ . ' "<br/>';echo '这是第"'. __LINE__ .'"行<br/>';//除非是根目录 否则不能包括末尾的斜杠echo '该文件位于"'. __DIR__ .'"';echo '命名空间为："', __NAMESPACE__, '"'; // 输出 "MyProject"//13.连接数据库echo "<h2>连接数据库</h2>";$servername = "www.qyying.cn";$username = "blog";$password = "123";$dbname = "myblog";//13.1 面向对象创建连接$conn0 = new mysqli($servername, $username, $password,$dbname);// 检测连接if ($conn0->connect_error) {die("连接失败: " . $conn0->connect_error);}echo "面向对象连接成功<br/>";//13.2 面向过程创建连接$conn1 = mysqli_connect($servername, $username, $password);// 检测连接if (!$conn1) {die("Connection failed: " . mysqli_connect_error());}mysqli_close($conn1);echo "面向过程连接成功<br/>";//13.3 PDO创建连接try {$conn2 = new PDO("mysql:host=$servername;dbname=myblog", $username, $password);$conn2=null;echo "PDO连接成功";}catch(PDOException $e){echo "出错啦".$e->getMessage()."<br/>";}//14.创建数据表//使用 sql 创建数据表$sql = "CREATE TABLE MyGuests (id INT(6) UNSIGNED AUTO_INCREMENT PRIMARY KEY,firstname VARCHAR(30) NOT NULL,lastname VARCHAR(30) NOT NULL,email VARCHAR(50),reg_date TIMESTAMP)";if ($conn0->query($sql) === TRUE){echo "Table MyGuests created successfully";}else{echo "创建数据表错误: " . $conn0->error;}/*//插入一条记录$sql = "INSERT INTO MyGuests (firstname, lastname, email)VALUES ('John', 'Doe', 'john@example.com')";if ($conn0->query($sql) === TRUE) {echo "新记录插入成功";} else {echo "Error: " . $sql . "<br>" . $conn0->error;}//插入多条记录$sql = "INSERT INTO MyGuests (firstname, lastname, email)VALUES ('John', 'Doe', 'john@example.com');";$sql .= "INSERT INTO MyGuests (firstname, lastname, email)VALUES ('Mary', 'Moe', 'mary@example.com');";$sql .= "INSERT INTO MyGuests (firstname, lastname, email)VALUES ('Julie', 'Dooley', 'julie@example.com')";if ($conn0->multi_query($sql) === TRUE) {echo "新记录插入成功";} else {echo "Error: " . $sql . "<br>" . $conn->error;}*/$sql = "SELECT id, firstname, lastname FROM MyGuests";$result = $conn0->query($sql);if ($result->num_rows > 0) {// 输出每行数据while($row = $result->fetch_assoc()){echo "<br> id: ". $row["id"]. " - Name: ". $row["firstname"]. " " . $row["lastname"];}}else{echo "0 个结果";}$conn0->close(); ?>
