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Agathe Andrieux
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Asked: 2022-05-17T12:51:05+00:00 In:

Simple solutions for the every derived table must have its own alias error.

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How to solve the problem – every derived table must have its own alias? I have the sample detail:

SELECT ID FROM (
  SELECT ID, msisdn
  FROM (
  SELECT * FROM TT2
  )
 );

While I was running it, I found the warning message:

Every derived table must have its own alias.

That is my question in my midterm exam, and it is urgent. I searched the solutions on some websites, but I didn’t get it. I may miss any line or other changes. I appreciate your assistance!

every derived table
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2 Answers

  1. Expert

    The cause: This issue is caused by the reason that you make a new table using your subquery for the FROM Command.

    If you don’t use the keyword AS to identify the alias for those queries, the DBMS query engine won’t be able to tell which query is which without knowing their names (or aliases).

    Solution:

    The requirement is that every derived table (AKA sub-query) needs to have an alias and each query in brackets must be having an alias that can be used to refer to it in the remainder of the outer query.

    SELECT ID FROM (
SELECT ID, msisdn FROM (
SELECT * FROM TT2
) AS T
) AS T

    You can replace the entire query with:

    SELECT ID FROM TT2
    • 23

  2. It’s asking you this: 

    SELECT ID
FROM (SELECT ID,
 msisdn 
 FROM (SELECT * FROM TT2) as myalias
 ) as anotheralias;

    Why would you ask this question?

    • 9

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