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https://issues.apache.org/jira/browse/ASTERIXDB-1560?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15404685#comment-15404685
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Yingyi Bu commented on ASTERIXDB-1560:
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[~dtabass], here is why we get this error message:
SELECT u.name AS uname, m.message AS message
FROM GleambookUsers u
UNNEST GleambookMessages m
WHERE m.authorId = user.id;
Since the symbol "user" is not defined, the compiler tries to resolve "user" as
abbreviatory field accesses (since we support implicit variable references
similar to SQL-92). Since the type of GleambookUsers and GleambookMessages
are open, "user" could potentially be a field of records from either dataset:
Possibility 1:
SELECT u.name AS uname, m.message AS message
FROM GleambookUsers u
UNNEST GleambookMessages m
WHERE m.authorId = u.user.id;
Possibility 2:
SELECT u.name AS uname, m.message AS message
FROM GleambookUsers u
UNNEST GleambookMessages m
WHERE m.authorId = m.user.id;
Therefore, it complains that there could ambiguous alias reference for "user",
i.e.:
u.user or m.user
Best,
Yingyi
> Misleading SQL++ error message when variables are undefined
> ------------------------------------------------------------
>
> Key: ASTERIXDB-1560
> URL: https://issues.apache.org/jira/browse/ASTERIXDB-1560
> Project: Apache AsterixDB
> Issue Type: Bug
> Components: AsterixDB, Error Reporting
> Reporter: Michael J. Carey
> Assignee: Yingyi Bu
> Priority: Minor
>
> This query:
> SELECT u.name AS uname, m.message AS message
> FROM GleambookUsers u
> UNNEST GleambookMessages m
> WHERE m.authorId = user.id;
> Yields this error message:
> Cannot resolve ambiguous alias (variable) reference for identifier user
> [AlgebricksException]
> The reference is undefined, not ambiguous, in this case.
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