多选题Which two operations can be performed on an external table（）ACreate a view on the table.BCreate an index on the table.CCreate a synonym on the table.DAdd a virtual column to the table.EUpdate the table using the UPDATE statement.FDelete rows in the tab

DROP USER SMITH；

DROP TABLE EMPLOYEES；

DROP TABLESPACE USERS；

ALTER TABLE SALES_REP DROP PARTITION P1；

ALTER TABLE EMPLOYEES DROP COLUMN DESIG_ID；

The index remains invisible.

The index is not updated by the DML statements on the indexed table.

The index automatically becomes visible in order to have it updated by DML on the table.

The index becomes unusable but the table is updated by the DML.

The index is updated by the DML on the table.

DROP USER SMITH；

DROP TABLE EMPLOYEES；

DROP TABLESPACE USERS；

ALTER TABLE SALES_REP DROP PARTITION P1；

ALTER TABLE EMPLOYEES DROP COLUMN DESIG_ID；

You can use aggregate functions in any clause of a SELECT statement.

You can use aggregate functions only in the column list of the SELECT clause and in the WHERE clause of a SELECT statement.

You can mix single row columns with aggregate functions in the column list of a SELECT statement by grouping on the single row columns.

You can pass column names, expressions, constants, or functions as parameters to an aggregate function.

You can use aggregate functions on a table, only by grouping the whole table as one single group.

You cannot group the rows of a table by more than one column while using aggregate functions.

Using a partial local Index on the warehouse fact table month column with indexing disabled to the table partitions that return most of their rows to the queries.

Using a partial local Index on the warehouse fact table month column with indexing disabled for the table partitions that return a few rows to the queries.

Using a partitioned view that does a UNION ALL query on the partitions of the warehouse fact table, which retains the existing local partitioned column.

Converting the partitioned table to a partitioned view that does a UNION ALL query on the monthly tables, which retains the existing local partitioned column

Using a partial global index on the warehouse fact table month column with indexing disabling for the table partitions that return most of their rows to the queries.

Using a partial global index on the warehouse fact table month column with indexing disabled for the table partitions that return a few rows to the queries.

Constraint names must start with SYS_C

All constraints must be defines at the column level

Constraints can be created after the table is created

Constraints can be created at the same time the table is created

Information about constraints is found in the VIEW_CONSTRAINTS dictionary view

Create a view on the table.

Create an index on the table.

Create a synonym on the table.

Add a virtual column to the table.

Update the table using the UPDATE statement.

Delete rows in the table using the DELETE command

You can use this feature to identify the committed versions of the rows， but not the uncommitted versions.

You can use this feature to identify the versions of V$ views.

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.

You can use this feature for a table only if row movement is enabled for the table.

You can use this feature to identify the versions of external and fixed tables.

An update in a leaf row takes place.

The index becomes invalid after the update.

The leaf block containing the row to be updated is marked as invalid.

A row in the leaf block of the index for the key value is deleted and inserted.

The row movement is not enabled on the table.

The first two updates were not explicitly committed.

The Flashback Versions Query lists only the most recent update.

The Flashback Versions Query stops producing rows after it encounters a time in the past when the  table structure was changed.

Finding queries that are not using indexes

Finding rows that are locked by InnoDB

Finding client connection attributes

Finding the part of a code in which a single query is spending time

Finding the size of each table

ALTER TABLE SPLIT PARTITION

ALTER TABLE MERGE PARTITION

ALTER TABLE TRUNCATE PARTITION

ALTER TABLE ADD PARTITION

ALTER TABLE DROP PARTITION

ALTER TABLE MOVE PARTITION

Create an INSERT trigger to assign the default value to each item in the table.

Create a CHECK constraint to validate the data and to assign the default value to each item in the table.

Create an UPDATE trigger to update the default value for each new item in the table.

Create a DEFAULT constraint to assign the default value specifying the WITH VALUES argument.

Create a view on the table.

Create an index on the table.

Create a synonym on the table.

Add a virtual column to the table.

Update the table using the UPDATE statement.

Delete rows in the table using the DELETE command.

A MERGE statement is used to merge the data of one table with data from another.

A MERGE statement replaces the data of one table with that of another.

A MERGE statement can be used to insert new rows into a table.

A MERGE statement can be used to update existing rows in a table.

A subquery that defines a view cannot include the GROUP BY clause

A view that is created with the subquery having the DISTINCT keyword can be updated

A view that is created with the subquery having the pseudo column ROWNUM keyword cannot be updated

A data manipulation language (DML) operation can be performed on a view that is created with the subquery having all the NOT NULL columns of a table