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Which two statements are true about the Automatic Workload Repository (AWR)? (Choose two.)A. All AWR tables belong to the SYSTEM schemaB. The AWR cont 阅读全文
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View the Exhibit and examine the attributes of an undo tablespace.In an OLTP system, the user SCOTT has started a query on a large table in the peak t 阅读全文
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Which statement is true regarding transactions? (Choose all that apply.)A. A transaction can consist only of a set of DML and DDL statements.B. A part 阅读全文
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Exists：子查询至少返回一行时条件为true。 Not Exists：子查询不返回任何一行时条件为true。 In：与子查询返回结果集中某个值相等。-- in null不会显示为null的值，因为null是未知的所以不会有=null，要查询为null的请用is null Not In：与子查询返 阅读全文
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View the Exhibit and examine the structure of the PRODUCTS table.You want to display the category with the maximum number of items.You issue the follo 阅读全文
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Which three statements are true about multiple-row subqueries? (Choose three.)A. They can contain a subquery within a subquery.B. They can return mult 阅读全文
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Which two statements are true regarding subqueries? (Choose two.)(关于子查询哪两句话是正确的？)A. A subquery can retrieve zero or more rows.（子查询能检索 0 行或多行）B. Only t 阅读全文