php连接mysql之mysqli操作集合

<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";

// 创建连接
$conn = new mysqli($servername, $username, $password, $dbname);
// 检测连接
if ($conn->connect_error) {
die("连接失败: " . $conn->connect_error);
}

// 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 ($conn->query($sql) === TRUE) {                        //$conn->query($sql) 是面向对象方法，mysqli_query($conn,$sql) 是面向过程方法，结果是一样的。
echo "Table MyGuests created successfully";
} else {
echo "创建数据表错误: " . $conn->error;
}

//插入数据
$sql = "INSERT INTO MyGuests (firstname, lastname, email)
VALUES ('John', 'Doe', 'john@example.com')";

if ($conn->query($sql) === TRUE) {
echo "新记录插入成功";
} else {
echo "Error: " . $sql . "<br>" . $conn->error;
}

//更新数据库中的数据
mysqli_query($conn,"UPDATE Persons SET Age=36
WHERE FirstName='Peter' AND LastName='Griffin'");

//删除数据库中的数据
mysqli_query($conn,"DELETE FROM Persons WHERE LastName='Griffin'");

//获取记录条数
$sql = "SELECT COUNT(uid) FROM user";
$count=$conn->query($sql) ;

//读取记录
$sql="select * from qa limit 0,10";
$result=$mysqli->query($sql);
while ($row = mysqli_fetch_assoc($result))
{
echo "{$row['question_title']} ";
echo "{$row['answer_content1']}";
}

//关闭数据库
$conn->close();
?>