Error while using substring in laravel query builder?

I am using substring to remove a string from database coulmn using query builder.But in this '?' treated as variable in query builder.Here is my code

->select( \DB::RAW("SUBSTRING_INDEX(
    SUBSTRING_INDEX(
    SUBSTRING_INDEX(
        SUBSTRING_INDEX(domain, '/', 3),'://', -1 ),'/',1),`?
         `,1)")
    ,'name',DB::RAW('MAX(datetime) as last_date'))

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