从开源博客系统Emlog里找了一段：
https://github.com/emlog/emlog/blob/master/src/admin/data.php

/**
 * 备份数据库结构和所有数据
 *
 * @param string $table 数据库表名
 * @return string
 */
function dataBak($table){
    $DB = MySql::getInstance();
    $sql = "DROP TABLE IF EXISTS $table;\n";
    $createtable = $DB->query("SHOW CREATE TABLE $table");
    $create = $DB->fetch_row($createtable);
    $sql .= $create[1].";\n\n";

    $rows = $DB->query("SELECT * FROM $table");
    $numfields = $DB->num_fields($rows);
    $numrows = $DB->num_rows($rows);
    while ($row = $DB->fetch_row($rows)){
        $comma = "";
        $sql .= "INSERT INTO $table VALUES(";
        for ($i = 0; $i < $numfields; $i++){
            $sql .= $comma."'".mysql_escape_string($row[$i])."'";
            $comma = ",";
        }
        $sql .= ");\n";
    }
    $sql .= "\n";
    return $sql;
}