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https://issues.apache.org/jira/browse/DERBY-2041?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13790354#comment-13790354
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Knut Anders Hatlen commented on DERBY-2041:
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The same problem exists with other SQL objects, such as functions. You can drop
a function that's used in a trigger body, but the trigger will fail when it
tries to invoke the function.
> Trigger should register a dependency on tables and columns used in its body
> ---------------------------------------------------------------------------
>
> Key: DERBY-2041
> URL: https://issues.apache.org/jira/browse/DERBY-2041
> Project: Derby
> Issue Type: Bug
> Components: SQL
> Affects Versions: 10.3.1.4
> Reporter: Bryan Pendleton
> Priority: Minor
> Labels: derby_triage10_11
>
> A trigger registers a dependency in the Dependency Manager for those columns
> which cause the firing of the trigger, but does not register a dependency on
> tables and columns which are used in the body of the trigger. This means that
> the trigger may unexpectedly become invalid due to a change to one of those
> tables and columns in its body, and the user may be surprised that Derby did
> not warn them of this problem when the underlying table/column change was
> made.
> An example of this problem is as follows:
> create table t1 (c1 int);
> create table t2 (c2 int);
> create trigger tr1 after update of c1 on t1 for each row mode db2sql insert
> into t2 (c2) values (1);
> With this set of definitions, Derby will warn/prevent the user about changes
> to table t1 and column c1, but will not warn the user about changes to table
> t2 and column c2. If the user drops or renames t2 or c2, the trigger will
> then give an error the next time it fires.
> It seems like it would be an improvement for the trigger to record this
> dependency on table t2 and column c2.
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