codd tables造句
例句与造句
- However Codd tables cannot represent the disjunction " result with possibly 0 or 1 rows ".
- The " forgetful " nature of the two sub-queries was all that it took to guarantee that some sure information went unreported when the above query was run on the Codd table Emp.
- Thus when unions are added to the query language, Codd tables are not even a weak representation system of missing information, meaning that queries over them don't even report all " sure " information.
- The intuition for what happens above is that the Codd tables representing the projections in the subqueries lose track of the fact that the Nulls in the columns F12 . F2 and F23 . F2 are actually copies of the originals in the table J . This observation suggests that a relatively simple improvement of Codd tables ( which works correctly for this example ) would be to use " Skolem constants " ( meaning Skolem functions which are also constant functions ), say ? 12 and ? 22 instead of a single NULL symbol.
- The intuition for what happens above is that the Codd tables representing the projections in the subqueries lose track of the fact that the Nulls in the columns F12 . F2 and F23 . F2 are actually copies of the originals in the table J . This observation suggests that a relatively simple improvement of Codd tables ( which works correctly for this example ) would be to use " Skolem constants " ( meaning Skolem functions which are also constant functions ), say ? 12 and ? 22 instead of a single NULL symbol.
- It's difficult to find codd tables in a sentence. 用codd tables造句挺难的