i'm running this question on mysql

 Choose ID FROM (Choose ID, msisdn FROM (Choose * FROM TT2))

which is giving this error:

Every derived table should have its very own alias.

what's wrong ?

Every derived table must indeed come with an alias.

Choose ID FROM (

    Choose ID, msisdn FROM (

        Choose * FROM TT2

    ) AS T

) AS T

Inside your situation, the whole query might be changed with:

Choose ID FROM TT2

I believe it's suggesting that you do that:

Choose ID FROM (Choose ID, msisdn FROM (Choose * FROM TT2) as myalias) as anotheralias

Why can you write this question to begin with?