> 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 http://www.upscene.com/ Professional Tools and Services for Firebird FB TraceManager, IB LogManager, Database Health Check, Tuning etc.
