在PHP7以上版本使用不了mysql扩展

旧程序使用了mysql扩展，而新环境却是PHP7以上版本，不支持mysql扩展，办法是将旧程序中的mysql相关内容修改为mysqli或PDO代码。

但是涉及修改的量大，那则可以包含(include "mysql.functions.php")此实现了mysql扩展的所有方法的兼容文件。

这里用mysqli扩展实现了原mysql扩展的所有方法，旧程序直接包含此文件即可，可以无需修改再修改其它代码。

mysql.functions.php : 

<?php
/**
 * php7 不支持mysql扩展的情况下，旧程序运行在PHP7环境下，直接通过公用文件包含此mysql扩展相关的函数包即可
 */
if (!function_exists('mysql_connect')) {
    if (!function_exists('mysqli_connect')) 
    {
        die("在PHP7.0以上版本兼容使用mysql扩展的旧程序，请先开启mysqli扩展！");
    }

    function mysql_connect(string $server,  $username,  $password, $new_link = false, $client_flags = 0)
    {
        $port = '3306';
        if (strpos($server, ':') !== false) {
            $host_port = explode(':', $server);
            $port = $host_port[1];
        }
        return mysqli_connect($server, $username, $password, '', $port);
    }

    function link_identifier_of(&$link_identifier = null)
    {
        if (is_null($link_identifier)) {
            $vars = array_merge($GLOBALS, get_defined_vars());
            $vars_len = count($vars);
            if ($vars_len > 0) {
                foreach ($vars as $var) {
                    $type =  gettype($var);
                    if ($type == 'object' && $var instanceof mysqli) {
                        $link_identifier = $var;
                        break;
                    }
                }
            }
        }
    }

    function mysql_error($link_identifier = null)
    {
        link_identifier_of($link_identifier);

        if (is_null($link_identifier)) {
            return mysqli_connect_error();
        }

        return mysqli_error($link_identifier);
    }

    function mysql_errno($link_identifier = null)
    {
        link_identifier_of($link_identifier);

        if (is_null($link_identifier)) {
            return mysqli_connect_errno();
        }

        return mysqli_errno($link_identifier);
    }



    function mysql_selectdb($database_name, $link_identifier)
    {
        return mysql_select_db($database_name, $link_identifier);
    }

    function mysql_select_db($database_name, $link_identifier = null)
    {
        link_identifier_of($link_identifier);
        return mysqli_select_db($link_identifier, $database_name);
    }

    function mysql_query($query, $link_identifier = null)
    {
        link_identifier_of($link_identifier);
        $resultmode = MYSQLI_STORE_RESULT;
        return mysqli_query($link_identifier, $query, $resultmode);
    }

    define('MYSQL_BOTH', MYSQLI_BOTH);
    define('MYSQL_ASSOC', MYSQLI_ASSOC);
    define('MYSQL_NUM', MYSQLI_NUM);

    function mysql_fetch_array($result, $result_type = MYSQL_BOTH)
    {
        return mysqli_fetch_array($result, $result_type);
    }

    function mysql_fetch_assoc($result)
    {
        return mysql_fetch_array($result, MYSQL_ASSOC);
    }

    function mysql_fetch_row($result)
    {
        return mysql_fetch_array($result, MYSQL_NUM);
    }

    function mysql_fetch_object($result, $class_name = 'stdClass', $params = null)
    {
        if (!$params) {
            $params = array();
        }

        return mysqli_fetch_object($result, $class_name, $params);
    }

    function mysql_fetch_lengths($result)
    {
        return mysqli_fetch_lengths($result);
    }

    function mysql_fetch_field($result, $field_offset = 0)
    {
        return mysqli_fetch_field_direct($result, $field_offset);
    }

    function mysql_field_name($result, $field_offset = 0)
    {

        if (is_object($result)) {
            $mysql_field = mysql_fetch_field($result, $field_offset);
            if (is_object($mysql_field)) {
                return $mysql_field->name;
            }
        }

        if (is_array($result)) {
            return $result["$field_offset"];
        }

        return null;
    }

    function mysql_field_len($result, $field_offset = 0)
    {
        $mysql_field = mysql_fetch_field($result, $field_offset);
        if (is_object($mysql_field)) {
            return $mysql_field->length;
        }
        return null;
    }


    function mysql_field_table($result, $field_offset = 0)
    {
        $mysql_field = mysql_fetch_field($result, $field_offset);
        if (is_object($mysql_field)) {
            return $mysql_field->table;
        }
        return null;
    }


    function mysql_field_type($result, $field_offset = 0)
    {
        $mysql_field = mysql_fetch_field($result, $field_offset);
        if (is_object($mysql_field)) {
            $type =  $mysql_field->type;

            switch ($type) {
                case MYSQLI_TYPE_VAR_STRING:
                case  MYSQLI_TYPE_STRING:
                    $type = 'string';
                    break;
                case MYSQLI_TYPE_LONG:
                case MYSQLI_TYPE_SHORT:
                case MYSQLI_TYPE_TINY:
                case MYSQLI_TYPE_LONGLONG:
                    $type = 'int';
                    break;
                case MYSQLI_TYPE_BLOB:
                case MYSQLI_TYPE_LONG_BLOB:
                case MYSQLI_TYPE_MEDIUM_BLOB:
                case MYSQLI_TYPE_TINY_BLOB:
                    $type = 'blob';
                    break;
                case MYSQLI_TYPE_CHAR:
                    $type = 'char';
                    break;
                default:
                    $type = 'string';
                    break;
            }
            return $type;
        }
        return null;
    }

    function mysql_field_flags($result, $field_offset)
    {
        $mysql_field = mysql_fetch_field($result, $field_offset);
        if (is_object($mysql_field)) {
            //return $mysql_field->flags;
        }
        return null;
    }

    function mysql_field_seek($result, $field_offset)
    {
        $mysql_field = mysql_fetch_field($result, $field_offset);
        if (is_object($mysql_field)) {
            //return $mysql_field->se;
        }
        return null;
    }

    function mysql_free_result($result)
    {
        $flag = true;
        try {
            mysqli_free_result($result);
        } catch (Exception $e) {
            $flag = false;
        }

        return $flag;
    }


    function mysql_close($link_identifier = null)
    {
        link_identifier_of($link_identifier);
        return mysqli_close($link_identifier);
    }

    function mysql_pconnect($server, $username, $password, $client_flags = null)
    {
        return mysql_connect($server, $username, $password, true, 0);
    }

    function mysql_stat($link_identifier = null)
    {
        link_identifier_of($link_identifier);
        return mysqli_stat($link_identifier);
    }

    function mysql_affected_rows($link_identifier = null)
    {
        link_identifier_of($link_identifier);
        return mysqli_affected_rows($link_identifier);
    }

    function mysql_client_encoding($link_identifier = null)
    {
        link_identifier_of($link_identifier);
        return mysqli_client_encoding($link_identifier);
    }

    function mysql_create_db($database_name, $link_identifier)
    {
        link_identifier_of($link_identifier);
        $query = "create database `$database_name`  default character set = 'utf8' ";
        $resultmode = MYSQLI_STORE_RESULT;
        return mysqli_query($link_identifier, $query, $resultmode);
    }

    function mysql_data_seek($result,  $row_number)
    {
        return mysqli_data_seek($result, $row_number);
    }


    function mysql_db_name($result, $row, $field = null)
    { 
        if (is_array($result)) {
            return $result["$row"];
        }
        mysql_data_seek($result, $row);
        $row = mysql_fetch_row($result);
        $dbname = $row[0];
        return $dbname;
    }

    function mysql_db_query($database, $query, $link_identifier = null)
    { 
        link_identifier_of($link_identifier);
        mysqli_select_db($link_identifier,$database);
        mysqli_query($link_identifier,$query);
    }

    function mysql_drop_db($database_name, $link_identifier)
    { 
        link_identifier_of($link_identifier);
        $result = mysqli_query($link_identifier, "drop `$database_name`");
        
        return $result;
    }

    function mysql_escape_string($unescaped_string, $link_identifier = null)
    {
        link_identifier_of($link_identifier);
        return mysqli_escape_string($link_identifier, $unescaped_string);
    }


    function mysql_real_escape_string($unescaped_string, $link_identifier = null)
    {
        link_identifier_of($link_identifier);
        return mysqli_real_escape_string($link_identifier, $unescaped_string);
    }

    function mysql_get_client_info()
    {
        return mysqli_get_client_info();
    }
    function mysql_get_host_info($link_identifier = null)
    {
        link_identifier_of($link_identifier);
        return mysqli_get_host_info($link_identifier);
    }

    function mysql_get_proto_info($link_identifier = null)
    {
        link_identifier_of($link_identifier);
        return mysqli_get_proto_info($link_identifier);
    }

    function mysql_get_server_info($link_identifier = null)
    {
        link_identifier_of($link_identifier);
        return mysqli_get_server_info($link_identifier);
    }

    function mysql_info($link_identifier = null)
    {
        link_identifier_of($link_identifier);
        return mysqli_info($link_identifier);
    }

    function mysql_insert_id($link_identifier = null)
    {
        link_identifier_of($link_identifier);
        return  mysqli_insert_id($link_identifier);
    }

    function mysql_list_dbs($link_identifier = null)
    {
        link_identifier_of($link_identifier);
        return mysqli_query($link_identifier, 'show databases');
    }

    function mysql_list_fields($database_name, $table_name, $link_identifier = null)
    {
        link_identifier_of($link_identifier);
        $result = mysqli_query($link_identifier, "DESCRIBE `$database_name`.`$table_name`");
        $column = array();
        while ($arr = mysqli_fetch_assoc($result)) {
            $column[] = $arr['Field'];
        }

        return $column;
    }

    function mysql_num_fields($result)
    {
        if ($result instanceof object) {
            return mysqli_num_fields($result);
        }

        if (is_array($result)) {
            return count($result);
        }

        return 0;
    }

    function mysql_list_processes($link_identifier = null)
    {
        link_identifier_of($link_identifier);
        $result = mysqli_query($link_identifier, "show processlist");
        return $result;
    }

    function mysql_list_tables($database, $link_identifier = null)
    {
        link_identifier_of($link_identifier);
        mysqli_query($link_identifier, "use `$database`");
        $result = mysqli_query($link_identifier, "show tables");
        return $result;
    }


    function mysql_num_rows($result)
    {
        if (is_array($result)) {
            return count($result);
        }

        return mysqli_num_rows($result);
    }

    function mysql_ping($link_identifier = null)
    {
        link_identifier_of($link_identifier);
        return mysqli_ping($link_identifier);
    }

    function mysql_result($result, $row = 0, $field = 0)
    {
        mysql_data_seek($result, $row);
        $arr = mysql_fetch_array($result);
        $column_result = $arr["$field"];
        if ($row != 0) {
            mysql_data_seek($result, 0);
        }

        return $column_result;
    }

    function mysql_set_charset($charset, $link_identifier = null)
    {
        link_identifier_of($link_identifier);
        return mysqli_set_charset($link_identifier, $charset);
    }

    function mysql_tablename($result, $i=0)
    {
        if (is_array($result)) {
            return $result["$i"];
        }

        mysql_data_seek($result, $i);
        $row = mysql_fetch_row($result);
        $tablename = $row[0];

        return $tablename;
    }

    function mysql_thread_id($link_identifier = null)
    {
        link_identifier_of($link_identifier);
        return mysqli_thread_id($link_identifier);
    }

    function mysql_unbuffered_query($query, $link_identifier = null)
    {
        link_identifier_of($link_identifier);
        return mysqli_query($link_identifier, $query);
    }
}
?>