PHP与MySQL交互

<?php
//连接数据库
$mysqli = new mysqli("localhost", "root", "", "test");

if(mysqli_connect_errno()){
	printf("Connect failed:%\n",mysqli_connect_error());
	exit();
} else {
	//建立表testtable
	$sql="create table testtable(id int not null primary 
         key auto_increment,testField varchar(75))";
	$res=mysqli_query($mysqli, $sql);
	if($res=true){
		echo "Table testtable successfully created.";
		//插入一条记录
		$sql_1="insert into testtable(testField) values
				('some value')";
		$res_1=mysqli_query($mysqli, $sql_1);
		if ($res_1=true) {
			echo "<br/>A record has been inserted.";
			//查询记录
			$sql_2="select * from testtable";
			$res_2=mysqli_query($mysqli, $sql_2);
			if ($res_2){
				//显示记录条数
				$number_of_rows = mysqli_num_rows($res_2);
				printf("<br/>Result set has %d rows.\n",$number_of_rows);
				//获取数据并显示结果
				while ($newArray = mysqli_fetch_array($res_2, MYSQLI_ASSOC)){
					$id = $newArray['id'];
					$testField = $newArray['testField'];
					echo "<br/>The ID is ".$id." and the text is ".$testField."<br/>";
				}
			} else {
				printf("Could not retrieve records:%s\n",mysqli_error($mysqli));
			}
		} else {
			printf("Could not insert record:%s\n",mysqli_error($mysqli));
		}
	} else {
		printf("Could not create table:%s\n",mysqli_error($mysqli));
	}
	
	mysqli_close($mysqli);
}