<?php

$host = "localhost";
$username = 'root';
$password = 'root';
$database = 'dbname';

$filters = ['content','payload'];

$pdo = new PDO("mysql:host={$host};dbname={$database}", $username, $password, array(PDO::ATTR_PERSISTENT => true));
$pdo->exec("set names 'utf8'");

$info = $pdo->query('SHOW TABLE STATUS;')->fetchAll(PDO::FETCH_ASSOC);

foreach ($info as $key => $value) {
      // 删除所有表注释
      $pdo->exec("ALTER TABLE " . $value['Name'] . " COMMENT '';");

      $info = $pdo->query("select * from information_schema.columns where table_name = '" . $value['Name'] . "'")->fetchAll(PDO::FETCH_ASSOC);
      foreach ($info as $i => $ivalue) {
　　　　　　　　// 删除整个数据库所有表中，存在在$filters数组中的列
              if (in_array($ivalue['COLUMN_NAME'], $filters)) {
                      $pdo->exec("ALTER TABLE " . $value['Name'] . " DROP COLUMN " . $ivalue['COLUMN_NAME'] . ";");
                      echo "删除表" . $value['Name'] . "中的：" . $ivalue['COLUMN_NAME'];
                      echo "  ";
              }
              // 删除所有表的所有字段的注释
              $pdo->exec("ALTER TABLE " . $value['Name'] . " MODIFY COLUMN " . $ivalue['COLUMN_NAME'] . " " .
                    $ivalue['COLUMN_TYPE'] . " COMMENT '';");
              echo "删除表" . $value['Name'] . "中的：" . $ivalue['COLUMN_NAME'] . "字段的注释";
              echo "  ";
      }
}