摘要

数据库操作类可以封装数据库连接和操作，使代码更易于维护和扩展。它们提供了一种组织代码的方法，将数据库相关的功能放在一个类中，以便于复用。

良好的数据库操作类可以提供一定程度的安全性，通过参数化查询或准备语句来防止SQL注入攻击。这有助于保护数据库免受恶意输入的影响。

良好的数据库操作类可以提供一定程度的安全性，通过参数化查询或准备语句来防止SQL注入攻击。这有助于保护数据库免受恶意输入的影响。

数据库操作类有助于提高PHP应用程序的可维护性、安全性和性能，同时促进代码的重用和更好的代码组织。然而，选择适合项目需求的数据库操作类以及正确使用它们非常重要。

Database.php

<?php

/**
 * PHP PDO MySQL数据库操作类
 * 作者：TANKING
 * 时间：2023-10-12
 * 博客：https://segmentfault.com/u/tanking
 */

class DB_API {
    private $pdo;
    private $error;
    
    // 连接数据库
    public function __construct($config) {
        $dsn = "mysql:host={$config['db_host']};port={$config['db_port']};dbname={$config['db_name']}";
        try {
            $this->pdo = new PDO($dsn, $config['db_user'], $config['db_pass']);
            $this->pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
        } catch (PDOException $e) {
            $this->error = $e->getMessage();
        }
    }
    
    // 插入
    public function add($table, $data) {
        try {
            $columns = implode(', ', array_keys($data));
            $values = implode(', :', array_keys($data));
            $query = "INSERT INTO $table ($columns) VALUES (:$values)";
            $stmt = $this->pdo->prepare($query);
            $stmt->execute($data);
            return $this->pdo->lastInsertId();
        } catch (PDOException $e) {
            $this->error = $e->getMessage();
            return false;
        }
    }
    
    // 更新
    public function update($table, $where, $data) {
        try {
            
            // 构建SET子句
            $set = '';
            foreach ($data as $key => $value) {
                $set .= "$key = :$key, ";
            }
            $set = rtrim($set, ', ');
    
            // 构建WHERE子句
            $whereClause = '';
            foreach ($where as $key => $value) {
                $whereClause .= "$key = :where_$key AND ";
            }
            $whereClause = rtrim($whereClause, 'AND ');
    
            // 构建SQL查询
            $query = "UPDATE $table SET $set WHERE $whereClause";
    
            // 创建预处理语句
            $stmt = $this->pdo->prepare($query);
    
            // 绑定更新数据的参数
            foreach ($data as $key => $value) {
                $stmt->bindValue(":$key", $value);
            }
    
            // 绑定WHERE条件的参数
            foreach ($where as $key => $value) {
                $stmt->bindValue(":where_$key", $value);
            }

            // 执行预处理语句
            $stmt->execute();
            
            // 操作成功
            return true;
    
        } catch (PDOException $e) {
            $this->error = $e->getMessage();
            
            // 操作失败
            return false;
        }
    }

    // 删除
    public function delete($table, $where, $params = array()) {
        try {
            // 构建WHERE子句
            $whereClause = '';
            foreach ($where as $key => $value) {
                $whereClause .= "$key = :$key AND ";
            }
            $whereClause = rtrim($whereClause, 'AND ');
    
            // 构建SQL查询
            $query = "DELETE FROM $table WHERE $whereClause";
    
            // 创建预处理语句
            $stmt = $this->pdo->prepare($query);
    
            // 绑定WHERE条件的参数
            foreach ($where as $key => $value) {
                $stmt->bindValue(":$key", $value);
            }
    
            // 执行预处理语句
            $stmt->execute();
    
            // 操作成功
            return true;
        } catch (PDOException $e) {
            $this->error = $e->getMessage();
            
            // 操作失败
            return false;
        }
    }

    // 查询
    public function select($table, $fields = "*", $conditions = null, $likeConditions = null, $orderBy = null, $limit = null, $params = array()) {
        try {
            // 构建SELECT子句
            if (is_array($fields)) {
                $fields = implode(', ', $fields);
            } elseif ($fields === "*") {
                $fields = "*";
            } else {
                $fields = "";
            }
    
            // 构建WHERE子句
            $whereClause = '';
            if (!is_null($conditions) && is_array($conditions)) {
                foreach ($conditions as $key => $value) {
                    $whereClause .= "$key = :$key AND ";
                }
                $whereClause = rtrim($whereClause, 'AND ');
            }
    
            // 合并LIKE条件
            if (!is_null($likeConditions) && is_array($likeConditions)) {
                if (!empty($whereClause)) {
                    $whereClause .= ' AND ';
                }
                foreach ($likeConditions as $key => $value) {
                    $whereClause .= "$key LIKE :like_$key AND ";
                    $params[":like_$key"] = $value;
                }
                $whereClause = rtrim($whereClause, 'AND ');
            }
    
            // 构建ORDER BY子句
            $orderByClause = '';
            if (!is_null($orderBy) && is_array($orderBy)) {
                $orderByClause = "ORDER BY " . implode(', ', $orderBy);
            }
    
            // 构建LIMIT子句
            $limitClause = '';
            if (!is_null($limit)) {
                $limitClause = "LIMIT $limit";
            }
    
            // 构建SQL查询
            $query = "SELECT $fields FROM $table";
            if (!empty($whereClause)) {
                $query .= " WHERE $whereClause";
            }
            if (!empty($orderByClause)) {
                $query .= " $orderByClause";
            }
            if (!empty($limitClause)) {
                $query .= " $limitClause";
            }
    
            // 创建预处理语句
            $stmt = $this->pdo->prepare($query);
    
            // 绑定参数
            if (!is_null($conditions) && is_array($conditions)) {
                foreach ($conditions as $key => $value) {
                    $stmt->bindValue(":$key", $value);
                }
            }
            
            if (!is_null($likeConditions) && is_array($likeConditions)) {
                foreach ($likeConditions as $key => $value) {
                    $stmt->bindValue(":like_$key", $value);
                }
            }
    
            // 执行预处理语句
            $stmt->execute();
    
            // 获取查询结果
            $result = $stmt->fetchAll(PDO::FETCH_ASSOC);
    
            return $result; // 返回查询结果数组
        } catch (PDOException $e) {
            $this->error = $e->getMessage();
            return false; // 操作失败
        }
    }

    // 执行原生SQL语句
    public function execQuery($query, $params = array()) {
        try {
            // 创建预处理语句
            $stmt = $this->pdo->prepare($query);
    
            // 绑定参数
            foreach ($params as $key => $value) {
                $stmt->bindValue($key, $value);
            }
    
            // 执行预处理语句
            $stmt->execute();
            
            // 操作成功
            return true;
        } catch (PDOException $e) {
            $this->error = $e->getMessage();
            
            // 操作失败
            return false;
        }
    }

    // 错误信息
    public function errorMsg() {
        return $this->error;
    }
}

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