PHP数据库连接函数：10个经典实例

在PHP中，进行数据库操作时，需要使用到数据库连接。PHP提供了多种连接数据库的方式，比如MySQLi、PDO等扩展。在这里，我们介绍一下10个经典的PHP数据库连接函数实例。

1. MySQLi连接函数

//连接MySQLi数据库
$mysqli = new mysqli("localhost", "username", "password", "database");

//判断连接是否成功
if ($mysqli->connect_error) {
    die('Connect Error (' . $mysqli->connect_errno . ') ' . $mysqli->connect_error);
}

2. PDO连接函数

//连接PDO数据库
try {
    $dbh = new PDO('mysql:host=localhost;dbname=database', 'username', 'password');
} catch (PDOException $e) {
    echo 'Connection failed: ' . $e->getMessage();
}

3. MySQLi查询函数

//执行MySQLi查询
$result = $mysqli->query("SELECT * FROM table");

//判断查询是否成功
if (!$result) {
    die('Query error: ' . $mysqli->error);
}

4. PDO查询函数

//执行PDO查询
$stmt = $dbh->query("SELECT * FROM table");

//判断查询是否成功
if (!$stmt) {
    echo "
PDO::errorInfo():
";
    print_r($dbh->errorInfo());
}

5. MySQLi插入函数

//执行MySQLi插入
$sql = "INSERT INTO table (column1, column2) VALUES ('$value1', '$value2')";

if ($mysqli->query($sql) === TRUE) {
    echo "New record created successfully";
} else {
    echo "Error: " . $sql . "<br>" . $mysqli->error;
}

6. PDO插入函数

//执行PDO插入
$sql = "INSERT INTO table (column1, column2) VALUES (?, ?)";
$stmt = $dbh->prepare($sql);
$stmt->execute(array($value1, $value2));

7. MySQLi更新函数

//执行MySQLi更新
$sql = "UPDATE table SET column1='$newvalue' WHERE id=$id";

if ($mysqli->query($sql) === TRUE) {
    echo "Record updated successfully";
} else {
    echo "Error updating record: " . $mysqli->error;
}

8. PDO更新函数

//执行PDO更新
$sql = "UPDATE table SET column1=? WHERE id=?";
$stmt = $dbh->prepare($sql);
$stmt->execute(array($newvalue, $id));

9. MySQLi删除函数

//执行MySQLi删除
$sql = "DELETE FROM table WHERE id=$id";

if ($mysqli->query($sql) === TRUE) {
    echo "Record deleted successfully";
} else {
    echo "Error deleting record: " . $mysqli->error;
}

10. PDO删除函数

//执行PDO删除
$sql = "DELETE FROM table WHERE id=?";
$stmt = $dbh->prepare($sql);
$stmt->execute(array($id));