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#171
 
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Re: Foreign keys -
01-17-2008
, 03:13 PM
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Not reading the whole thread (big mistake on my part), but how about the instance where a foreign key can be null?. No functional dependecy but legit. |
before.
Decompose the table into two tables, one of which only contains the PK and
the FK under discussion. Now, when the FK would have received a null, omit
the entire tuple (row),
since it conveys no information.
Nulls drop out of the discussion, and it proceeds as before.
#172
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Not reading the whole thread (big mistake on my part), but how about the instance where a foreign key can be null?. No functional dependecy but legit. |
before.
Decompose the table into two tables, one of which only contains the PK and
the FK under discussion. Now, when the FK would have received a null, omit
the entire tuple (row),
since it conveys no information.
Nulls drop out of the discussion, and it proceeds as before.
#173
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Not reading the whole thread (big mistake on my part), but how about the instance where a foreign key can be null?. No functional dependecy but legit. |
before.
Decompose the table into two tables, one of which only contains the PK and
the FK under discussion. Now, when the FK would have received a null, omit
the entire tuple (row),
since it conveys no information.
Nulls drop out of the discussion, and it proceeds as before.
#174
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Not reading the whole thread (big mistake on my part), but how about the instance where a foreign key can be null?. No functional dependecy but legit. |
before.
Decompose the table into two tables, one of which only contains the PK and
the FK under discussion. Now, when the FK would have received a null, omit
the entire tuple (row),
since it conveys no information.
Nulls drop out of the discussion, and it proceeds as before.
#175
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Not reading the whole thread (big mistake on my part), but how about the instance where a foreign key can be null?. No functional dependecy but legit. |
before.
Decompose the table into two tables, one of which only contains the PK and
the FK under discussion. Now, when the FK would have received a null, omit
the entire tuple (row),
since it conveys no information.
Nulls drop out of the discussion, and it proceeds as before.
#176
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Not reading the whole thread (big mistake on my part), but how about the instance where a foreign key can be null?. No functional dependecy but legit. |
before.
Decompose the table into two tables, one of which only contains the PK and
the FK under discussion. Now, when the FK would have received a null, omit
the entire tuple (row),
since it conveys no information.
Nulls drop out of the discussion, and it proceeds as before.
#177
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Not reading the whole thread (big mistake on my part), but how about the instance where a foreign key can be null?. No functional dependecy but legit. |
before.
Decompose the table into two tables, one of which only contains the PK and
the FK under discussion. Now, when the FK would have received a null, omit
the entire tuple (row),
since it conveys no information.
Nulls drop out of the discussion, and it proceeds as before.
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