php mysql上传图片

在PHP中使用MySQL上传图片通常涉及以下几个步骤：

基础概念

文件上传：允许用户通过网页表单选择并上传文件到服务器。
数据库存储：将文件的元数据（如文件名、路径、上传时间等）存储在数据库中。
文件系统存储：将实际的文件保存在服务器的文件系统中。

类型

直接存储：将文件内容直接存储在数据库的BLOB（Binary Large Object）字段中。
间接存储：仅存储文件的路径在数据库中，文件本身保存在文件系统。

应用场景

用户头像上传
产品图片上传
文档管理系统

示例代码

HTML表单

<!DOCTYPE html>
<html>
<head>
    <title>Upload Image</title>
</head>
<body>
    <form action="upload.php" method="post" enctype="multipart/form-data">
        Select image to upload:
        <input type="file" name="fileToUpload" id="fileToUpload">
        <input type="submit" value="Upload Image" name="submit">
    </form>
</body>
</html>

PHP处理脚本（upload.php）

<?php
$target_dir = "uploads/";
$target_file = $target_dir . basename($_FILES["fileToUpload"]["name"]);
$imageFileType = strtolower(pathinfo($target_file,PATHINFO_EXTENSION));

// Check if image file is a actual image or fake image
if(isset($_POST["submit"])) {
    $check = getimagesize($_FILES["fileToUpload"]["tmp_name"]);
    if($check !== false) {
        echo "File is an image - " . $check["mime"] . ".";
    } else {
        echo "File is not an image.";
        exit;
    }
}

// Check if file already exists
if (file_exists($target_file)) {
    echo "Sorry, file already exists.";
    exit;
}

// Check file size
if ($_FILES["fileToUpload"]["size"] > 500000) {
    echo "Sorry, your file is too large.";
    exit;
}

// Allow certain file formats
if($imageFileType != "jpg" && $imageFileType != "png" && $imageFileType != "jpeg"
&& $imageFileType != "gif" ) {
    echo "Sorry, only JPG, JPEG, PNG & GIF files are allowed.";
    exit;
}

// Check if $uploadOk is set to 0 by an error
if ($uploadOk == 0) {
    echo "Sorry, your file was not uploaded.";
// if everything is ok, try to upload file
} else {
    if (move_uploaded_file($_FILES["fileToUpload"]["tmp_name"], $target_file)) {
        echo "The file ". htmlspecialchars( basename( $_FILES["fileToUpload"]["name"])). " has been uploaded.";

        // Save file path to database
        $servername = "localhost";
        $username = "username";
        $password = "password";
        $dbname = "database_name";

        // Create connection
        $conn = new mysqli($servername, $username, $password, $dbname);
        // Check connection
        if ($conn->connect_error) {
            die("Connection failed: " . $conn->connect_error);
        }

        $sql = "INSERT INTO images (name, path) VALUES (?, ?)";
        $stmt = $conn->prepare($sql);
        $stmt->bind_param("ss", $fileName, $filePath);
        $fileName = basename($_FILES["fileToUpload"]["name"]);
        $filePath = $target_file;

        if ($stmt->execute()) {
            echo "New record created successfully";
        } else {
            echo "Error: " . $sql . "<br>" . $stmt->error;
        }

        $stmt->close();
        $conn->close();
    } else {
        echo "Sorry, there was an error uploading your file.";
    }
}
?>