問題文
A developer loads twenty rows into a table and later runs a query on it with no ORDER BY clause. The rows come back in a sequence that differs from the sequence they were loaded in. Which statement describes how a relational table holds its rows?
選択肢
- A table holds an unordered set of rows and a query hands them back in whatever sequence the database server finds cheapest to produce.
- A table holds rows in the sequence they were loaded and a query hands back that same sequence until some of those rows are deleted.
- A table holds rows grouped by the block they occupy and a query hands back the blocks in ascending order of the block number.
- A table holds rows sorted by the primary key and a query hands back that key order whenever the key column values stay unchanged.