单选题The ST_INFO master table has millions of rows that are updated very rarely. It has a STATE_CODE column that contains the value for 25 states. The table is frequently queried on the STATE_CODE column.  Which type of index would you suggest to improve th

第1题：

A warehouse fact table in your Oracle 12c Database is range-partitioned by month and accessed frequently with queries that span multiple partitions The table has a local prefixed, range partitioned index. Some of these queries access very few rows in some partitions and all the rows in other partitions, but these queries still perform a full scan for all accessed partitions. This commonly occurs when the range of dates begins at the end of a month or ends close to the start of a month. You want an execution plan to be generated that uses indexed access when only a few rows are accessed from a segment, while still allowing full scans for segments where many rows are returned. Which three methods could transparently help to achieve this result?（）

• A、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.
• B、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.
• C、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.
• D、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
• E、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.
• F、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.

第2题：

An index called ORD_CUSTNAME_IX has been created on the CUSTNAME column in the ORDERS table using the following command：   SQL>CREATE INDEX ord_custname_ix ON orders（custname）；   The ORDERS table is frequently queried using the CUSTNAME column in the WHERE clause. You want to check the impact on the performance of the queries if the index is not available. You do not want the index to be dropped or rebuilt to perform this test.  Which is the most efficient method of performing this task？（）

• A、 disabling the index
• B、 making the index invisible
• C、 making the index unusable
• D、 using the MONITORING USAGE clause for the index

第3题：

The ST_INFO master table has millions of rows that are updated very rarely. It has a STATE_CODE column that contains the value for 25 states. The table is frequently queried on the STATE_CODE column. Which type of index would you suggest to improve the query performance？（）

• A、B-tree
• B、bitmap
• C、reverse key
• D、function based

第4题：

The EMPLOYEES table has these columns: LAST_NAME VARCHAR2(35) SALARY NUMBER(8,2) HIRE_DATE DATE Management wants to add a default value to the SALARY column. You plan to alter the table by using this SQL statement: ALTER TABLE EMPLOYEES MODIFY (SALARY DEFAULT 5000); Which is true about your ALTER statement?（）

• A、Column definitions cannot be altered to add DEFAULT values.
• B、A change to the DEFAULT value affects only subsequent insertions to the table.
• C、Column definitions cannot be altered to add DEFAULT values for columns with a NUMBER data type.
• D、All the rows that have a NULL value for the SALARY column will be updated with the value 5000.

第5题：

You have a server that has very limited memory but has a very large table. You will use mysqldump to back up this table. Which option will ensure mysqldump will process a row at a time instead of buffering a set of rows?（）

• A、— quick
• B、— skip-buffer
• C、— single-transaction
• D、— tab

第6题：

You work in a company which is named Wiikigo Corp. The company uses SQL Server 2008. You are the administrator of the company database. Now you are in charge of a SQL Server 2008 instance. There is a database which is named Sellings in the instance. The Sellings database contains a table named Productions. The table is used to stores information about all types of products. The Productions table is often queried by users on the basis of the RadioSize column. The RadioSize column contains the NULL value for all products other than Radios. Currently no index exists on the RadionSize column. According to the requirement of the company CIO, you have to optimize the query performance and reduce the effect on the disk space to the least. So what action should you perform to achieve this goal?（）  

• A、On the Products table, you should create a view. 
• B、On the RadioSize column, you should create a clustered index 
• C、On the RadioSize column, you should create a filtered index 
• D、On the RadioSize column, you should create a unique clustered index

第7题：

第8题：

第9题：

第10题：

第11题：

第12题：

第13题：

The EMPLOYEES table has these columns: LAST NAME VARCHAR2(35) SALARY NUMBER(8,2) HIRE_DATE DATE Management wants to add a default value to the SALARY column. You plan to alter the table by using this SQL statement: ALTER TABLE EMPLOYEES MODIFY ( SALARY DEFAULT 5000); What is true about your ALTER statement?（）

• A、Column definitions cannot be altered to add DEFAULT values.
• B、A change to the DEFAULT value affects only subsequent insertions to the table.
• C、Column definitions cannot be altered at add DEFAULT values for columns with a NUMBER data type.
• D、All the rows that have a NULL value for the SALARY column will be updated with the value 5000.

第14题：

As a result of performance analysis， you created an index on the prod_name column of the prod_det table， which contains about ten thousand rows. Later， you updated a product name in the table. How does this change affect the index？（）

• A、A leaf will be marked as invalid.
• B、An update in a leaf row takes place.
• C、The index will be updated automatically at commit.
• D、A leaf row in the index will be deleted and inserted.
• E、The index becomes invalid when you make any updates.

第15题：

You need to change the definition of an existing table. The COMMERCIALS table needs its DESCRIPTION column changed to hold varying length characters up to 2000 bytes. The column can currently hold 1000 bytes per value. The table contains 20000 rows. Which statement is valid?（）

• A、ALTER TABLE commercials MODIFY (description CHAR2(2000));
• B、ALTER TABLE commercials CHANGE (description CHAR2(2000));
• C、ALTER TABLE commercials CHANGE (description VARCHAR2 (2000));
• D、ALTER TABLE commercials MODIFY (description VARCHAR2 (2000));
• E、You cannot increase the size of a column if the table has rows.

第16题：

The SCOTT user has an index on the ITEM_DESC column of the ITEM table. As part of the year-ending task， SCOTT updates the ITEM_DESC column for most of the rows in the ITEM table. How does this change to the table affect the index？（）

• A、An update in a leaf row takes place.
• B、The index becomes invalid after the update.
• C、The leaf block containing the row to be updated is marked as invalid.
• D、A row in the leaf block of the index for the key value is deleted and inserted.

第17题：

You are modifying a table named Product in a SQL Server 2005 database. You want to add a new column named FriendlyName to the Product table. A friendly name for each product will be stored in this column. The table currently contains data. The sales department has not yet created a friendly name for each product. FriendlyName is a required value for each product. You want to add this new column by using the least amount of effort. What should you do？（）

• A、Define the new column as NULL.Update the FriendlyName column to the same value as the productName column. Alter the FriendlyName column to be NOT NULL.
• B、Define the new column as NOT NULL with a default value of ’Undefined.’
• C、Define the new column as NULL. Use application logic to enforce the data constraint.
• D、Define the new column as NULL with a default value of ’Undefined.’

第18题：

第19题：

第20题：

第21题：

第22题：

第23题：