PHP--MySQL简明手册
PHP 的MySQL链接
当用PHP访问数据库时，除了PHP自带的数据库驱动，咱们通常还有两种比较好的选择：PDO和MySQLi。php
注意：自PHP5.5开始，传统的mysql扩展已经废弃，只能使用PHP提供的MySQLi扩展或PDO扩展html
PDO和MySQLi区别
| PDO | MySQLi | |
|---|---|---|
| Database support | 12 different drivers | MySQL only |
| API | OOP | OOP + procedural |
| Connection | Easy | Easy |
| Named parameters | Yes | No |
| Object mapping | Yes | Yes |
| Prepared statements (client side) | Yes | No |
| Performance | Fast | Fast |
| Stored procedures | Yes | Yes |
若是你的项目须要在多种数据库中切换，建议使用 PDO;若选用MySQLi,在多种数据库中切换时候，你须要从新编写全部代码。mysql
MySQLi专门针对MySQL设计的，因此MySQLi相对于PDO性能稍微好一些。sql
PHP 链接MySQL
MySQLi - 面向对象的链接方法数据库
<?php
$servername = "localhost";
$username = "username";
$password = "password";
// 建立链接
$conn = new mysqli($servername, $username, $password);
// 检测链接
if ($conn->connect_error) {
die("链接失败: " . $conn->connect_error);
}
echo "链接成功";
?>
MySQLi - 面向过程的链接方法数组
<?php
$servername = "localhost";
$username = "username";
$password = "password";
// 建立链接
$conn = mysqli_connect($servername,
$username, $password);
// 检测链接
if (!$conn) {
die("Connection
failed: " . mysqli_connect_error());
}
echo "链接成功";
?
PDO 的链接方法服务器
<?php
$servername = "localhost";
$username = "username";
$password = "password";
try {
$conn = new PDO("mysql:host=$servername;dbname=myDB",
$username, $password);
echo "链接成功";
}
catch(PDOException $e)
{
echo $e->getMessage();
}
?>
关闭链接
链接在脚本执行完后会自动关闭。可使用如下代码来关闭链接：并发
MySQLi - 面向对象的关闭链接方法app
$conn->close();
MySQLi - 面向过程的关闭链接方法ide
mysqli_close($conn);
PDO关闭链接的方法
$conn = null;
建立数据库
使用 MySQLi 和 PDO 建立 MySQL 数据库
使用CREATE DATABASE语句建立数据库
MySQLi - 使用面向对象的方式建立数据库
<?php
$servername = "localhost";
$username = "username";
$password = "password";
// 建立链接
$conn = new mysqli($servername, $username, $password);
// 检测链接
if ($conn->connect_error) {
die("链接失败: " . $conn->connect_error);
}
// 建立数据库
$sql = "CREATE DATABASE myDB";
if ($conn->query($sql) === TRUE) {
echo "数据库建立成功";
} else {
echo
"Error creating database: " . $conn->error;
}
$conn->close();
?>
MySQLi-使用面向过程的方式建立数据库
<?php
$servername = "localhost";
$username = "username";
$password = "password";
// 建立链接
$conn = mysqli_connect($servername,
$username, $password);
// 检测链接
if (!$conn) {
die("链接失败: " . mysqli_connect_error());
}
// 建立数据库
$sql = "CREATE DATABASE myDB";
if (mysqli_query($conn, $sql)) {
echo "数据库建立成功";
} else {
echo "Error
creating database: " . mysqli_error($conn);
}
mysqli_close($conn);
?>
PDO 建立数据库
<?php
$servername = "localhost";
$username = "username";
$password = "password";
try {
$conn = new PDO("mysql:host=$servername;dbname=myDB", $username, $password);
// 设置 PDO 错误模式为异常
$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$sql = "CREATE DATABASE myDBPDO";
// 使用 exec() ，由于没有结果返回
$conn->exec($sql);
echo "数据库建立成功<br>";
}
catch(PDOException $e)
{
echo $sql . "<br>" . $e->getMessage();
}
$conn = null;
?>
建立数据表
使用CREATE TABLE语句建立数据表
咱们将建立一个名为 "MyGuests" 的表，有 5 个列： "id", "firstname", "lastname", "email" 和 "reg_date":
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 )
MySQLi - 使用面向对象的方式建立数据表
<?php
$servername = "localhost";
$username = "username";
$password =
"password";
$dbname = "myDB";
// 建立链接
$conn =
new mysqli($servername, $username, $password, $dbname);
// 检测链接
if ($conn->connect_error) {
die("链接失败: " . $conn->connect_error);
}
// 使用 sql 建立数据表
$sql = "CREATE TABLE MyGuests (
id INT(6) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
firstname VARCHAR(30) NOT NULL,
lastname VARCHAR(30) NOT NULL,
email VARCHAR(50),
reg_date TIMESTAMP
)";
if ($conn->query($sql) === TRUE) {
echo "Table MyGuests created successfully";
} else {
echo "建立数据表错误: " . $conn->error;
}
$conn->close();
?>
MySQLi - 使用面向过程的方式建立数据表
<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";
// 建立链接
$conn = mysqli_connect($servername, $username, $password, $dbname);
// 检测链接
if (!$conn) {
die("链接失败: " . mysqli_connect_error());
}
// 使用 sql 建立数据表
$sql = "CREATE TABLE MyGuests (
id INT(6) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
firstname VARCHAR(30) NOT NULL,
lastname VARCHAR(30) NOT NULL,
email VARCHAR(50),
reg_date TIMESTAMP
)";
if (mysqli_query($conn, $sql)) {
echo "数据表 MyGuests 建立成功";
} else {
echo "建立数据表错误: " . mysqli_error($conn);
}
mysqli_close($conn);
?>
PDO 建立数据表
<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDBPDO";
try {
$conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
// 设置 PDO 错误模式，用于抛出异常
$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
// 使用 sql 建立数据表
$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
)";
// 使用 exec() ，没有结果返回
$conn->exec($sql);
echo "数据表 MyGuests 建立成功";
}
catch(PDOException $e)
{
echo $sql . "<br>" . $e->getMessage();
}
$conn = null;
?>
插入数据
插入语句
INSERT INTO table_name (column1, column2, column3,...)VALUES (value1, value2, value3,...)
MySQLi - 使用面向对象方式插入数据
<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";
// 建立链接
$conn = new mysqli($servername, $username, $password, $dbname);
// 检测链接
if ($conn->connect_error) {
die("链接失败: " . $conn->connect_error);
}
$sql = "INSERT INTO MyGuests (firstname, lastname, email)
VALUES ('John', 'Doe', 'john@example.com')";
if ($conn->query($sql) === TRUE) {
echo "新记录插入成功";
} else {
echo "Error: " . $sql . "<br>" . $conn->error;
}
$conn->close();
?>
MySQLi - 使用面向过程方式插入数据
<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";
// 建立链接
$conn = mysqli_connect($servername, $username, $password, $dbname);
// 检测链接
if (!$conn) {
die("Connection failed: " . mysqli_connect_error());
}
$sql = "INSERT INTO MyGuests (firstname, lastname, email)
VALUES ('John', 'Doe', 'john@example.com')";
if (mysqli_query($conn, $sql)) {
echo "新记录插入成功";
} else {
echo "Error: " . $sql . "<br>" . mysqli_error($conn);
}
mysqli_close($conn);
?>
POD 插入数据
<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDBPDO";
try {
$conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
// 设置 PDO 错误模式，用于抛出异常
$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$sql = "INSERT INTO MyGuests (firstname, lastname, email)
VALUES ('John', 'Doe', 'john@example.com')";
// 使用 exec() ，没有结果返回
$conn->exec($sql);
echo "新记录插入成功";
}
catch(PDOException $e)
{
echo $sql . "<br>" . $e->getMessage();
}
$conn = null;
?>
插入多条数据
MySQLi - 使用面向对象方式插入多条数据
<?php
$servername = "localhost";
$username = "username";
$password =
"password";
$dbname = "myDB";
// 建立连接
$conn = new mysqli($servername, $username, $password, $dbname);
// 检查连接
if ($conn->connect_error) {
die("链接失败: " . $conn->connect_error);
}
$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');";
$sql .= "INSERT INTO MyGuests (firstname, lastname, email)
VALUES ('Julie', 'Dooley', 'julie@example.com')";
if ($conn->multi_query($sql) === TRUE) {
echo "新记录插入成功";
} else {
echo "Error: " . $sql . "<br>" . $conn->error;
}
$conn->close();
?>
MySQLi - 使用面向过程方式插入多条数据
<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";
// 建立连接
$conn = mysqli_connect($servername, $username, $password, $dbname);
// 检查连接
if (!$conn) {
die("链接失败: " . mysqli_connect_error());
}
$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');";
$sql .= "INSERT INTO MyGuests (firstname, lastname, email)
VALUES ('Julie', 'Dooley', 'julie@example.com')";
if (mysqli_multi_query($conn, $sql)) {
echo "新记录插入成功";
} else {
echo "Error: " . $sql . "<br>" . mysqli_error($conn);
}
mysqli_close($conn);
?>
PDO 插入多条数据
<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDBPDO";
try {
$conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
// set the PDO error mode to exception
$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
// 开始事务
$conn->beginTransaction();
// SQL 语句
$conn->exec("INSERT INTO MyGuests (firstname, lastname, email)
VALUES ('John', 'Doe', 'john@example.com')");
$conn->exec("INSERT INTO MyGuests (firstname, lastname, email)
VALUES ('Mary', 'Moe', 'mary@example.com')");
$conn->exec("INSERT INTO MyGuests (firstname, lastname, email)
VALUES ('Julie', 'Dooley', 'julie@example.com')");
// 提交事务
$conn->commit();
echo "新记录插入成功";
}
catch(PDOException $e)
{
// 若是执行失败回滚
$conn->rollback();
echo $sql . "<br>" . $e->getMessage();
}
$conn = null;
?>
使用预处理语句插入多条数据
<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";
// 建立链接
$conn = new mysqli($servername, $username, $password, $dbname);
// 检测链接
if ($conn->connect_error) {
die("链接失败: " . $conn->connect_error);
} else {
$sql = "INSERT INTO MyGuests VALUES(?, ?, ?)";
// 为 mysqli_stmt_prepare() 初始化statement 对象
$stmt = mysqli_stmt_init($conn);
//预处理语句
if (mysqli_stmt_prepare($stmt, $sql)) {
// 绑定参数
mysqli_stmt_bind_param($stmt, 'sss', $firstname, $lastname, $email);
// 设置参数并执行
$firstname = 'John';
$lastname = 'Doe';
$email = 'john@example.com';
mysqli_stmt_execute($stmt);
$firstname = 'Mary';
$lastname = 'Moe';
$email = 'mary@example.com';
mysqli_stmt_execute($stmt);
$firstname = 'Julie';
$lastname = 'Dooley';
$email = 'julie@example.com';
mysqli_stmt_execute($stmt);
}
}
?>
参数绑定
mysqli_stmt_bind_param($stmt, 'sss', $firstname, $lastname, $email);
该函数绑定参数查询并将参数传递给数据库。第二个参数是 "sss" 。如下列表展现了参数的类型。
- i - 整数
- d - 双精度浮点数
- s - 字符串
- b - 布尔值
预处理语句
预处理：建立 SQL 语句模板并发送到数据库。预留的值使用参数 '?' 标记 。数据库解析，编译，对SQL语句模板执行查询优化，并存储结果不输出。最后，将应用绑定的值传递给参数（"?" 标记），数据库执行语句
相对直接执行SQL语句，预处理的优势：
- 预处理语句大大减小了分析时间，只作了一次查询（虽然语句屡次执行）。
- 绑定参数减小了服务器带宽，你只须要发送查询的参数，而不是整个语句。
- 预处理语句针对SQL注入是很是有用的，由于参数值发送后使用不一样的协议，保证了数据的合法性。
MySQLi 使用预处理语句
<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";
// 建立链接
$conn = new mysqli($servername, $username, $password, $dbname);
// 检测链接
if ($conn->connect_error)
{
die("链接失败: " . $conn->connect_error);
}
// 预处理及绑定
$stmt = $conn->prepare("INSERT INTO MyGuests (firstname, lastname, email)
VALUES(?, ?, ?)");
$stmt->bind_param("sss", $firstname, $lastname, $email);
// 设置参数并执行
$firstname = "John";
$lastname = "Doe";
$email = "john@example.com";
$stmt->execute();
$firstname = "Mary";
$lastname = "Moe";
$email = "mary@example.com";
$stmt->execute();
$firstname = "Julie";
$lastname = "Dooley";
$email = "julie@example.com";
$stmt->execute();
echo "新记录插入成功";
$stmt->close();
$conn->close();
?>
PDO 使用预处理语句
<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDBPDO";
try {
$conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
// 设置 PDO 错误模式为异常
$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
// 预处理 SQL 并绑定参数
$stmt = $conn->prepare("INSERT INTO MyGuests (firstname, lastname, email)
VALUES (:firstname, :lastname, :email)");
$stmt->bindParam(':firstname', $firstname);
$stmt->bindParam(':lastname', $lastname);
$stmt->bindParam(':email', $email);
// 插入行
$firstname = "John";
$lastname = "Doe";
$email = "john@example.com";
$stmt->execute();
// 插入其余行
$firstname = "Mary";
$lastname = "Moe";
$email = "mary@example.com";
$stmt->execute();
// 插入其余行
$firstname = "Julie";
$lastname = "Dooley";
$email = "julie@example.com";
$stmt->execute();
echo "新记录插入成功";
}
catch(PDOException $e)
{
echo $sql . "<br>" . $e->getMessage();
}
$conn = null;
?>
查询数据
MySQLi -使用面向对象方式查询数据
<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";
// 建立链接
$conn = new mysqli($servername, $username, $password, $dbname);
// 检测链接
if ($conn->connect_error)
{
die("链接失败: " . $conn->connect_error);
}
$sql = "SELECT id, firstname, lastname FROM MyGuests";
$result = $conn->query($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";
}
$conn->close();
?>
PDO 查询数据
<?php
echo "<table style='border: solid 1px black;'>";
echo "<tr><th>Id</th><th>Firstname</th><th>Lastname</th><th>Email</th><th>Reg date</th> </tr>";
class TableRows extends RecursiveIteratorIterator {
function __construct($it) {
parent::__construct($it, self::LEAVES_ONLY);
}
function current() {
return "<td style='width: 150px; border: 1px solid black;'>" .
parent::current(). "</td>";
}
function beginChildren() {
echo "<tr>";
}
function endChildren() {
echo "</tr>" . "\n";
}
}
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDBPDO";
try {
$conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$stmt = $conn->prepare("SELECT * FROM MyGuests");
$stmt->execute();
// 设置结果集为关联数组
$result = $stmt->setFetchMode(PDO::FETCH_ASSOC);
foreach(new TableRows(new RecursiveArrayIterator($stmt->fetchAll())) as $k=>$v) {
echo $v;
}
$dsn = null;
}
catch(PDOException $e)
{
echo "Error: " . $e->getMessage();
}
$conn = null;
echo "</table>";
?>
使用 WHERE 子句
WHERE 子句用于提取知足指定标准的的记录。
语法：
SELECT column_name(s) FROM table_name WHERE column_name operator value
例子：
<?php
$con=mysqli_connect("localhost","username","password","database");
// 检测链接
if (mysqli_connect_errno())
{
echo "链接失败: " . mysqli_connect_error();
}
$sql = "SELECT * FROM Persons WHERE FirstName='Peter'";
$result = mysqli_query($con,$sql);
while($row = mysqli_fetch_array($result))
{
echo $row['FirstName'] . " " . $row['LastName'];
echo "<br>";
}
?>
ORDER BY 关键词
ORDER BY 关键词用于对记录集中的数据进行排序，默认为升序。
语法：
SELECT column_name(s) FROM table_name ORDER BY column_name(s) ASC|DESC
例子：
<?php
$con=mysqli_connect("localhost","username","password","database");
// 检测链接
if (mysqli_connect_errno())
{
echo "链接失败: " . mysqli_connect_error();
}
$sql = "SELECT * FROM Persons ORDER BY age";
$result = mysqli_query($con,$sql);
while($row = mysqli_fetch_array($result))
{
echo $row['FirstName'];
echo " " . $row['LastName'];
echo " " . $row['Age'];
echo "<br>";
}
mysqli_close($con);
?>
根据两列进行排序
能够根据多个列进行排序.
当按照多个列进行排序时，只有第一列的值相同时才使用第二列：
SELECT column_name(s) FROM table_name ORDER BY column1, column2
Update 更新数据
UPDATE 语句用于更新数据库表中已存在的记录。
语法：
UPDATE table_name SET column1=value, column2=value2,... WHERE some_column=some_value
注意：若是省去 WHERE 子句，全部的记录都会被更新！
假设已经建立了“Person表”：
| FirstName | LastName | Age |
|---|---|---|
| Peter | Griffin | 35 |
| Glenn | Quagmire | 33 |
对Person表更新
<?php
$con=mysqli_connect("localhost","username","password","database");
// 检测链接
if (mysqli_connect_errno())
{
echo "链接失败: " . mysqli_connect_error();
}
$sql = "UPDATE Persons SET Age=36 WHERE FirstName='Peter' AND LastName='Griffin'";
mysqli_query($con,$sql);
mysqli_close($con);
?>
更新后：
| FirstName | LastName | Age |
|---|---|---|
| Peter | Griffin | 36 |
| Glenn | Quagmire | 33 |
Delete 删除数据
DELETE 语句用于从数据库表中删除行。
语法：
DELETE FROM table_name WHERE some_column = some_value
注意：若是省去 WHERE 子句，全部的记录都会被删除！
假设有表Person
| FirstName | LastName | Age |
|---|---|---|
| Peter | Griffin | 35 |
| Glenn | Quagmire | 33 |
下面的例子删除 "Persons" 表中全部 LastName='Griffin' 的记录：
<?php
$con=mysqli_connect("localhost","username","password","database");
// 检测链接
if (mysqli_connect_errno())
{
echo "链接失败: " . mysqli_connect_error();
}
$sql = "DELETE FROM Persons WHERE LastName='Griffin'";
mysqli_query($con,$sql);
mysqli_close($con);
?>
删除数据后：
| FirstName | LastName | Age |
|---|---|---|
| Glenn | Quagmire | 33 |
参考
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