[jira] Updated: (DERBY-4658) Allow explicit casts of string values to BOOLEAN

["Rick Hillegas (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/DERBY-4658?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Rick Hillegas updated DERBY-4658:
---------------------------------

    Attachment: derby-4658-01-aa-booleanCasts.diff

Attaching derby-4658-01-aa-booleanCasts.diff. This patch makes it possible to cast values to BOOLEAN. I need to run regression tests.

Makes the following changes:

1) Makes parser accept CAST (... AS BOOLEAN)

2) Allows those casts to succeed provided that the source datatype is a string and the actual value satisfies the SQL Standard's rules.

3) Adds regression tests for this feature.

Touches the following files:

--------------

M      java/engine/org/apache/derby/impl/sql/compile/sqlgrammar.jj

Parser now accepts explicit casts to BOOLEAN.

--------------

M      java/engine/org/apache/derby/impl/sql/compile/CastNode.java
M      java/engine/org/apache/derby/impl/sql/compile/BooleanConstantNode.java
M      java/engine/org/apache/derby/iapi/types/SQLBoolean.java

Standard support for the string value "UNKNOWN".

--------------

M      java/testing/org/apache/derbyTesting/functionTests/tests/lang/BooleanValuesTest.java

Regression tests.


> Allow explicit casts of string values to BOOLEAN
> ------------------------------------------------
>
>                 Key: DERBY-4658
>                 URL: https://issues.apache.org/jira/browse/DERBY-4658
>             Project: Derby
>          Issue Type: Improvement
>          Components: SQL
>            Reporter: Rick Hillegas
>            Assignee: Rick Hillegas
>         Attachments: derby-4658-01-aa-booleanCasts.diff
>
>
> The SQL Standard allows strings to be explicitly cast to BOOLEAN values. Strings are the only type (other than BOOLEAN itself) which can be cast to BOOLEAN. As part of our expanding support for the BOOLEAN datatype, we should allow these casts.
> Casting string types to boolean is defined by part 2, section 6.12 (<cast specification>), general rule 20:
> a) Trim whitespace off the string
> b) Then apply the rules in section 5.3 (<literal>). This means that the trimmed string must be 'TRUE', 'FALSE', or 'UNKNOWN', regardless of case.
> c) Otherwise, raise an exception.

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