[jira] [Commented] (DERBY-2072) Implement CAST from INTEGER (and other numeric types) to VARCHAR

["Lukas Eder (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/DERBY-2072?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17154473#comment-17154473 ] 

Lukas Eder commented on DERBY-2072:
-----------------------------------

For the record, this can be circumvented by casting to CHAR first:

{code}
VALUES CAST(CAST(123 AS CHAR(38)) AS VARCHAR(10))
{code}

> Implement CAST from INTEGER (and other numeric types) to VARCHAR
> ----------------------------------------------------------------
>
>                 Key: DERBY-2072
>                 URL: https://issues.apache.org/jira/browse/DERBY-2072
>             Project: Derby
>          Issue Type: Improvement
>          Components: SQL
>            Reporter: Christian d'Heureuse
>            Priority: Major
>              Labels: derby_triage10_11
>
> While CASTs from DATE/TIME to VARCHAR and from INTEGER to CHAR are allowed, the conversion from INTEGER to VARCHAR is not supported.
> The statement
>   VALUES CAST(123 as VARCHAR(10))
> produces the error
>   Cannot convert types 'INTEGER' to 'VARCHAR'.
> The function org.apache.derby.impl.sql.compile.BaseTypeCompiler.numberConvertible() returns false for a conversion from INTEGER to VARCHAR. This is documented within a comment in the source code, but it's not documented why.this is so.
> (Another documented rule in numberConvertible() is that floating point types can only be converted to CHAR by the CHAR() function and not with a CAST. There is also no indication of why this is so.)
> See also DERBY-1289, DERBY-1306 and DERBY-1804.



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