core/Mysql.php
public function dropField(string $tbname, string $field)
    {
        if ($this->existsField($tbname, $field)) {
            $sql = "ALTER TABLE {$tbname} DROP `{$field}`;";
            return $this->exec($sql);
        }
        return null;
    }
public function dropField(string $tbname, string $field)
    {
        if ($this->existsField($tbname, $field)) {
            $sql = "ALTER TABLE {$tbname} DROP `{$field}`;";
            return $this->exec($sql);
        }
        return null;
    }
删除字段
@param string $tbname
@param string $field
@return int|null
@throws MysqlException