Subject Re: [firebird-support] Foreign key different field type
Author Thomas Steinmaurer
> Hi,
> Can someone show me example when it is usefull to have different field
> type in relation
> Sample
> Create table test1 (id smallint not null primary key)
> Create table test2 (id1 integer)
> Alter table test2 Add foreign key (id1) references test1(id)
> Why this is not forbidden?

Perhaps cause the referenced column in table test1 can only store a
subset (SMALLINT) of the value range of the INTEGER used in test2?

Even if this works at DDL time, I wonder how strict the optimizer then
is in JOIN statements using an index. Haven't tried.

At DDL time: What happens if you flip the used data types for ID/ID1?

With regards,
Thomas Steinmaurer

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