Home/ Questions/Recommendation for the subquery in from must have an alias error.
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Charlotte Thomas
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Asked: 2022-05-18T20:01:56+00:00 In:

Recommendation for the subquery in from must have an alias error.

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Hi developer experts, I have a small but frustrating use case, and so far, I couldn’t get my head around this problem & ideal solution. I am running my command and facing one problem with the subquery in from must have an alias. Below is the command I used:

SELECT COUNT (made_only_recharge) AS made_only_recharge
 FROM (
  SELECT DISTINCT (identifiant) AS made_only_recharge
  FROM cdr_data
  WHERE CALLEDNUMBER = '0130'
  EXCEPT
  SELECT DISTINCT (identifiant) AS made_only_recharge
  FROM cdr_data
  WHERE CALLEDNUMBER != '0130'
 )

When I run it, I get the following error:

[Err] ERROR:
LINE 3: FROM (SELECT DISTINCT (identifiant) AS made_only_recharge

I am looking forward to gaining some knowledge from all experts. Thank you, guys!

subquery in from
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2 Answers

  1. Best Answer
    Expert

    The cause:

    In the FROM clause, you did not set for the subquery an alias (such as a name), so it could not be identified in the query and the error happened.

    Solution:

    You can fix this error by adding an ALIAS to the subquery in the FROM clause as following:

    SELECT COUNT(made_only_recharge) AS made_only_recharge
FROM
(
SELECT DISTINCT (identifiant) AS made_only_recharge
FROM cdr_data
WHERE CALLEDNUMBER = '0130'
EXCEPT
SELECT DISTINCT (identifiant) AS made_only_recharge
FROM cdr_data
WHERE CALLEDNUMBER != '0130'
) AS derivedTable
    • 0

  2. Some DBMS require nested tables to be named MySQL or Oracle, while others don’t have this strict requirement but allow you to add them to replace the inner query.

    • 7

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