PHP--MySQL簡明手冊
PHP 的MySQL鏈接
當用PHP訪問數據庫時，除了PHP自帶的數據庫驅動，咱們通常還有兩種比較好的選擇：PDO和MySQLi。php
注意：自PHP5.5開始，傳統的mysql擴展已經廢棄，只能使用PHP提供的MySQLi擴展或PDO擴展html
PDO和MySQLi區別
| 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 |
若是你的項目須要在多種數據庫中切換，建議使用 PDO;若選用MySQLi,在多種數據庫中切換時候，你須要從新編寫全部代碼。mysql
MySQLi專門針對MySQL設計的，因此MySQLi相對於PDO性能稍微好一些。sql
PHP 鏈接MySQL
MySQLi - 面向對象的鏈接方法數據庫
<?php
$servername = "localhost";
$username = "username";
$password = "password";
// 建立鏈接
$conn = new mysqli($servername, $username, $password);
// 檢測鏈接
if ($conn->connect_error) {
die("鏈接失敗: " . $conn->connect_error);
}
echo "鏈接成功";
?>
MySQLi - 面向過程的鏈接方法數組
<?php
$servername = "localhost";
$username = "username";
$password = "password";
// 建立鏈接
$conn = mysqli_connect($servername,
$username, $password);
// 檢測鏈接
if (!$conn) {
die("Connection
failed: " . mysqli_connect_error());
}
echo "鏈接成功";
?
PDO 的鏈接方法服務器
<?php
$servername = "localhost";
$username = "username";
$password = "password";
try {
$conn = new PDO("mysql:host=$servername;dbname=myDB",
$username, $password);
echo "鏈接成功";
}
catch(PDOException $e)
{
echo $e->getMessage();
}
?>
關閉鏈接
鏈接在腳本執行完後會自動關閉。可使用如下代碼來關閉鏈接：併發
MySQLi - 面向對象的關閉鏈接方法app
$conn->close();
MySQLi - 面向過程的關閉鏈接方法ide
mysqli_close($conn);
PDO關閉鏈接的方法
$conn = null;
建立數據庫
使用 MySQLi 和 PDO 建立 MySQL 數據庫
使用CREATE DATABASE語句建立數據庫
MySQLi - 使用面向對象的方式建立數據庫
<?php
$servername = "localhost";
$username = "username";
$password = "password";
// 建立鏈接
$conn = new mysqli($servername, $username, $password);
// 檢測鏈接
if ($conn->connect_error) {
die("鏈接失敗: " . $conn->connect_error);
}
// 建立數據庫
$sql = "CREATE DATABASE myDB";
if ($conn->query($sql) === TRUE) {
echo "數據庫建立成功";
} else {
echo
"Error creating database: " . $conn->error;
}
$conn->close();
?>
MySQLi-使用面向過程的方式建立數據庫
<?php
$servername = "localhost";
$username = "username";
$password = "password";
// 建立鏈接
$conn = mysqli_connect($servername,
$username, $password);
// 檢測鏈接
if (!$conn) {
die("鏈接失敗: " . mysqli_connect_error());
}
// 建立數據庫
$sql = "CREATE DATABASE myDB";
if (mysqli_query($conn, $sql)) {
echo "數據庫建立成功";
} else {
echo "Error
creating database: " . mysqli_error($conn);
}
mysqli_close($conn);
?>
PDO 建立數據庫
<?php
$servername = "localhost";
$username = "username";
$password = "password";
try {
$conn = new PDO("mysql:host=$servername;dbname=myDB", $username, $password);
// 設置 PDO 錯誤模式爲異常
$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$sql = "CREATE DATABASE myDBPDO";
// 使用 exec() ，由於沒有結果返回
$conn->exec($sql);
echo "數據庫建立成功<br>";
}
catch(PDOException $e)
{
echo $sql . "<br>" . $e->getMessage();
}
$conn = null;
?>
建立數據表
使用CREATE TABLE語句建立數據表
咱們將建立一個名爲 "MyGuests" 的表，有 5 個列： "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 - 使用面向對象的方式建立數據表
<?php
$servername = "localhost";
$username = "username";
$password =
"password";
$dbname = "myDB";
// 建立鏈接
$conn =
new mysqli($servername, $username, $password, $dbname);
// 檢測鏈接
if ($conn->connect_error) {
die("鏈接失敗: " . $conn->connect_error);
}
// 使用 sql 建立數據表
$sql = "CREATE TABLE MyGuests (
id INT(6) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
firstname VARCHAR(30) NOT NULL,
lastname VARCHAR(30) NOT NULL,
email VARCHAR(50),
reg_date TIMESTAMP
)";
if ($conn->query($sql) === TRUE) {
echo "Table MyGuests created successfully";
} else {
echo "建立數據表錯誤: " . $conn->error;
}
$conn->close();
?>
MySQLi - 使用面向過程的方式建立數據表
<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";
// 建立鏈接
$conn = mysqli_connect($servername, $username, $password, $dbname);
// 檢測鏈接
if (!$conn) {
die("鏈接失敗: " . mysqli_connect_error());
}
// 使用 sql 建立數據表
$sql = "CREATE TABLE MyGuests (
id INT(6) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
firstname VARCHAR(30) NOT NULL,
lastname VARCHAR(30) NOT NULL,
email VARCHAR(50),
reg_date TIMESTAMP
)";
if (mysqli_query($conn, $sql)) {
echo "數據表 MyGuests 建立成功";
} else {
echo "建立數據表錯誤: " . mysqli_error($conn);
}
mysqli_close($conn);
?>
PDO 建立數據表
<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDBPDO";
try {
$conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
// 設置 PDO 錯誤模式，用於拋出異常
$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
// 使用 sql 建立數據表
$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() ，沒有結果返回
$conn->exec($sql);
echo "數據表 MyGuests 建立成功";
}
catch(PDOException $e)
{
echo $sql . "<br>" . $e->getMessage();
}
$conn = null;
?>
插入數據
插入語句
INSERT INTO table_name (column1, column2, column3,...)VALUES (value1, value2, value3,...)
MySQLi - 使用面向對象方式插入數據
<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";
// 建立鏈接
$conn = new mysqli($servername, $username, $password, $dbname);
// 檢測鏈接
if ($conn->connect_error) {
die("鏈接失敗: " . $conn->connect_error);
}
$sql = "INSERT INTO MyGuests (firstname, lastname, email)
VALUES ('John', 'Doe', 'john@example.com')";
if ($conn->query($sql) === TRUE) {
echo "新記錄插入成功";
} else {
echo "Error: " . $sql . "<br>" . $conn->error;
}
$conn->close();
?>
MySQLi - 使用面向過程方式插入數據
<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";
// 建立鏈接
$conn = mysqli_connect($servername, $username, $password, $dbname);
// 檢測鏈接
if (!$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 "新記錄插入成功";
} else {
echo "Error: " . $sql . "<br>" . mysqli_error($conn);
}
mysqli_close($conn);
?>
POD 插入數據
<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDBPDO";
try {
$conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
// 設置 PDO 錯誤模式，用於拋出異常
$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$sql = "INSERT INTO MyGuests (firstname, lastname, email)
VALUES ('John', 'Doe', 'john@example.com')";
// 使用 exec() ，沒有結果返回
$conn->exec($sql);
echo "新記錄插入成功";
}
catch(PDOException $e)
{
echo $sql . "<br>" . $e->getMessage();
}
$conn = null;
?>
插入多條數據
MySQLi - 使用面向對象方式插入多條數據
<?php
$servername = "localhost";
$username = "username";
$password =
"password";
$dbname = "myDB";
// 建立連接
$conn = new mysqli($servername, $username, $password, $dbname);
// 檢查連接
if ($conn->connect_error) {
die("鏈接失敗: " . $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 "新記錄插入成功";
} else {
echo "Error: " . $sql . "<br>" . $conn->error;
}
$conn->close();
?>
MySQLi - 使用面向過程方式插入多條數據
<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";
// 建立連接
$conn = mysqli_connect($servername, $username, $password, $dbname);
// 檢查連接
if (!$conn) {
die("鏈接失敗: " . 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 "新記錄插入成功";
} else {
echo "Error: " . $sql . "<br>" . mysqli_error($conn);
}
mysqli_close($conn);
?>
PDO 插入多條數據
<?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);
// 開始事務
$conn->beginTransaction();
// SQL 語句
$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')");
// 提交事務
$conn->commit();
echo "新記錄插入成功";
}
catch(PDOException $e)
{
// 若是執行失敗回滾
$conn->rollback();
echo $sql . "<br>" . $e->getMessage();
}
$conn = null;
?>
使用預處理語句插入多條數據
<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";
// 建立鏈接
$conn = new mysqli($servername, $username, $password, $dbname);
// 檢測鏈接
if ($conn->connect_error) {
die("鏈接失敗: " . $conn->connect_error);
} else {
$sql = "INSERT INTO MyGuests VALUES(?, ?, ?)";
// 爲 mysqli_stmt_prepare() 初始化statement 對象
$stmt = mysqli_stmt_init($conn);
//預處理語句
if (mysqli_stmt_prepare($stmt, $sql)) {
// 綁定參數
mysqli_stmt_bind_param($stmt, 'sss', $firstname, $lastname, $email);
// 設置參數並執行
$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);
}
}
?>
參數綁定
mysqli_stmt_bind_param($stmt, 'sss', $firstname, $lastname, $email);
該函數綁定參數查詢並將參數傳遞給數據庫。第二個參數是 "sss" 。如下列表展現了參數的類型。
- i - 整數
- d - 雙精度浮點數
- s - 字符串
- b - 布爾值
預處理語句
預處理：建立 SQL 語句模板併發送到數據庫。預留的值使用參數 '?' 標記 。數據庫解析，編譯，對SQL語句模板執行查詢優化，並存儲結果不輸出。最後，將應用綁定的值傳遞給參數（"?" 標記），數據庫執行語句
相對直接執行SQL語句，預處理的優勢：
- 預處理語句大大減小了分析時間，只作了一次查詢（雖然語句屢次執行）。
- 綁定參數減小了服務器帶寬，你只須要發送查詢的參數，而不是整個語句。
- 預處理語句針對SQL注入是很是有用的，由於參數值發送後使用不一樣的協議，保證了數據的合法性。
MySQLi 使用預處理語句
<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";
// 建立鏈接
$conn = new mysqli($servername, $username, $password, $dbname);
// 檢測鏈接
if ($conn->connect_error)
{
die("鏈接失敗: " . $conn->connect_error);
}
// 預處理及綁定
$stmt = $conn->prepare("INSERT INTO MyGuests (firstname, lastname, email)
VALUES(?, ?, ?)");
$stmt->bind_param("sss", $firstname, $lastname, $email);
// 設置參數並執行
$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 "新記錄插入成功";
$stmt->close();
$conn->close();
?>
PDO 使用預處理語句
<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDBPDO";
try {
$conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
// 設置 PDO 錯誤模式爲異常
$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
// 預處理 SQL 並綁定參數
$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();
// 插入其餘行
$firstname = "Mary";
$lastname = "Moe";
$email = "mary@example.com";
$stmt->execute();
// 插入其餘行
$firstname = "Julie";
$lastname = "Dooley";
$email = "julie@example.com";
$stmt->execute();
echo "新記錄插入成功";
}
catch(PDOException $e)
{
echo $sql . "<br>" . $e->getMessage();
}
$conn = null;
?>
查詢數據
MySQLi -使用面向對象方式查詢數據
<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";
// 建立鏈接
$conn = new mysqli($servername, $username, $password, $dbname);
// 檢測鏈接
if ($conn->connect_error)
{
die("鏈接失敗: " . $conn->connect_error);
}
$sql = "SELECT id, firstname, lastname FROM MyGuests";
$result = $conn->query($sql);
if ($result->num_rows > 0) {
// 輸出每行數據
while($row = $result->fetch_assoc())
{
echo "<br> id: ". $row["id"]. " - Name: ". $row["firstname"]. " " . $row["lastname"];
}
} else {
echo "0 個結果";
}
$conn->close();
?>
PDO 查詢數據
<?php
echo "<table style='border: solid 1px black;'>";
echo "<tr><th>Id</th><th>Firstname</th><th>Lastname</th><th>Email</th><th>Reg date</th> </tr>";
class TableRows extends RecursiveIteratorIterator {
function __construct($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();
// 設置結果集爲關聯數組
$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 子句用於提取知足指定標準的的記錄。
語法：
SELECT column_name(s) FROM table_name WHERE column_name operator value
例子：
<?php
$con=mysqli_connect("localhost","username","password","database");
// 檢測鏈接
if (mysqli_connect_errno())
{
echo "鏈接失敗: " . 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 關鍵詞
ORDER BY 關鍵詞用於對記錄集中的數據進行排序，默認爲升序。
語法：
SELECT column_name(s) FROM table_name ORDER BY column_name(s) ASC|DESC
例子：
<?php
$con=mysqli_connect("localhost","username","password","database");
// 檢測鏈接
if (mysqli_connect_errno())
{
echo "鏈接失敗: " . 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);
?>
根據兩列進行排序
能夠根據多個列進行排序.
當按照多個列進行排序時，只有第一列的值相同時才使用第二列：
SELECT column_name(s) FROM table_name ORDER BY column1, column2
Update 更新數據
UPDATE 語句用於更新數據庫表中已存在的記錄。
語法：
UPDATE table_name SET column1=value, column2=value2,... WHERE some_column=some_value
注意：若是省去 WHERE 子句，全部的記錄都會被更新！
假設已經建立了「Person表」：
| FirstName | LastName | Age |
|---|---|---|
| Peter | Griffin | 35 |
| Glenn | Quagmire | 33 |
對Person表更新
<?php
$con=mysqli_connect("localhost","username","password","database");
// 檢測鏈接
if (mysqli_connect_errno())
{
echo "鏈接失敗: " . mysqli_connect_error();
}
$sql = "UPDATE Persons SET Age=36 WHERE FirstName='Peter' AND LastName='Griffin'";
mysqli_query($con,$sql);
mysqli_close($con);
?>
更新後：
| FirstName | LastName | Age |
|---|---|---|
| Peter | Griffin | 36 |
| Glenn | Quagmire | 33 |
Delete 刪除數據
DELETE 語句用於從數據庫表中刪除行。
語法：
DELETE FROM table_name WHERE some_column = some_value
注意：若是省去 WHERE 子句，全部的記錄都會被刪除！
假設有表Person
| FirstName | LastName | Age |
|---|---|---|
| Peter | Griffin | 35 |
| Glenn | Quagmire | 33 |
下面的例子刪除 "Persons" 表中全部 LastName='Griffin' 的記錄：
<?php
$con=mysqli_connect("localhost","username","password","database");
// 檢測鏈接
if (mysqli_connect_errno())
{
echo "鏈接失敗: " . mysqli_connect_error();
}
$sql = "DELETE FROM Persons WHERE LastName='Griffin'";
mysqli_query($con,$sql);
mysqli_close($con);
?>
刪除數據後：
| FirstName | LastName | Age |
|---|---|---|
| Glenn | Quagmire | 33 |
參考
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