单选题Which statement is true regarding Flashback Version Query？（）AIt returns versions of rows only within a transaction.BIt can be used in subqueries contained only in a SELECT statement.CIt will return an error if the undo retention time is less than the l

第1题：

Which statements are true regarding the Query Result Cache？（） 

• A、 It can be set at the system， session， or table level.
• B、 It is used only across statements in the same session.
• C、 It can store the results from normal as well as flashback queries.
• D、 It can store the results of queries based on normal，temporary，and dictionary tables.

第2题：

You executed the following query：  SELECT operation， undo_sql， table_name FROM flashback_transaction_query； Which statement is correct regarding the query output？（）

• A、 It would return information regarding only the last committed transaction.
• B、 It would return only the active transactions in all the undo segments in the database.
• C、 It would return only the committed transactions in all the undo segments in the database.
• D、 It would return both active and committed transactions in all the undo segments in the database.
• E、 It would return information regarding the transactions that began and were committed in the last 30 minutes.

第3题：

Which two are true about aggregate functions? （）

• A、You can use aggregate functions in any clause of a SELECT statement.
• B、You can use aggregate functions only in the column list of the select clause and in the WHERE clause of a SELECT statement.
• C、You can mix single row columns with aggregate functions in the column list of a SELECT statement by grouping on the single row columns.
• D、You can pass column names, expressions, constants, or functions as parameter to an aggregate function.
• E、You can use aggregate functions on a table, only by grouping the whole table as one single group.
• F、You cannot group the rows of a table by more than one column while using aggregate functions.

第4题：

What is true regarding subqueries?（）

• A、The inner query always sorts the results of the outer query
• B、The outer query always sorts the results of the inner query
• C、The outer query must return a value to the outer query
• D、The inner query returns a value to the outer query
• E、The inner query must always return a value or the outer query will give an error

第5题：

Which two statements about subqueries are true? （）

• A、A single row subquery can retrieve data from only one table.
• B、A SQL query statement cannot display data from table B that is referred to in its subquery, unless table B is included in the main query's FROM clause.
• C、A SQL query statement can display data from table B that is referred to in its subquery, without including B in its own FROM clause.
• D、A single row subquery can retrieve data from more than one table.
• E、A single row subquery cannot be used in a condition where the LIKE operator is used for comparison.
• F、A multiple-row subquery cannot be used in an INSERT statement to insert multiple rows at a time.

第6题：

By mistake， you ran the batch job （for updating the BILL_DETAILS table） twice. You are not sure which rows in the BILL_DETAILS table were affected. You need to identify：  a） A list of changes made along with the transaction identifier of each change.  b） The necessary SQL statements to undo the erroneous changes.  Which option would you choose？（）

• A、 RMAN only.
• B、 Flashback Table only.
• C、 Flashback Version Query only.
• D、 Flashback Database and Flashback Transaction Query.
• E、 Flashback Version Query and Flashback Transaction Query.

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第13题：

Which two statements about subqueries are true? （）

• A、A subquery should retrieve only one row.
• B、A subquery can retrieve zero or more rows.
• C、A subquery can be used only in SQL query statements.
• D、Subqueries CANNOT be nested by more than two levels.
• E、A subquery CANNOT be used in an SQL query statement that uses group functions.
• F、When a subquery is used with an inequality comparison operator in the outer SQL statement, the column list in the SELECT clause of the subquery should contain only one column.

第14题：

You are maintaining your OLTP database in Oracle10g. You are performing the Flashback Transaction Query to find the undo SQL statements that can be used to undo the changes made to the database in the specific time period. Which pseudocolumn will you use to perform the Flashback Transaction Query？（）

• A、 VERSIONS_STARTSCN
• B、 VERSIONS_STARTTIME
• C、 VERSIONS_XID
• D、 VERSIONS_OPERATION

第15题：

Which two statements are correct regarding the Flashback Versions Query feature？（）

• A、 You can use this feature to identify the committed versions of the rows， but not the uncommitted versions.
• B、 You can use this feature to identify the versions of V$ views.
• C、 You can use this feature to identify the inserts， deletes， and updates performed on a particular row but not the data definition language （DDL） operations performed on the table.
• D、 You can use this feature for a table only if row movement is enabled for the table.
• E、 You can use this feature to identify the versions of external and fixed tables.

第16题：

Which two statements are true regarding subqueries? （）

• A、A subquery can retrieve zero or more rows 
• B、Only two subqueries can be placed atone level 
• C、A subquery can be used only in SQL query statements 
• D、A subquery can appear on either side of a comparison operator 
• E、There is no limit on the number of subquery levels in the WHERE clause of a SELECT statement 

第17题：

Which statement is true regarding Flashback Version Query？ （）

• A、 It returns versions of rows only within a transaction.
• B、 It can be used in subqueries contained only in a SELECT statement.
• C、 It will return an error if the undo retention time is less than the lower bound time or SCN specified.
• D、 It retrieves all versions including the deleted as well as subsequently reinserted versions of the rows.

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