You are managing an Oracle Database 10g database that uses Oracle Managed Files （OMF）. You enabled the block change tracking feature for the database. Which statement regarding the change tracking file is true？（） One block change tracking file is created for each data file. By default， the file is created in DB_CREATE_FILE_DEST.。 One block change tracking file is created for each data file. By default， the file is created in BACKGROUND_DUMP_DEST.。 One block change tracking file is created for the database. By default， the file is created in DB_CREATE_FILE_DEST.。 One block change tracking file is created for the database. By default， the file is created in BACKGROUND_DUMP_DEST.。
The accounting manager wants you to create a form that when queried will display a calculated total of year-to-date actual expenditures for the fund code entered. The value needed to generate this summary data are stored in multiple tables. How would you define the data source for this data block without having the DBA create a database object? （） Choose Tools -> Data Block Wizard, select View as the data source type, and base the block on the columns from the bales. 。 Choose Tools -> Data Block Wizard, select Table as the data source type, and base the block on the columns from the tables. 。 Select the Data Blocks node in the Object Navigator and click the Create button. Choose to build the data block manually and alter the Query Data Source Columns and Query Data Source Arguments properties to enter the SELECT statement. 。 Select the Data Blocks node in the Object Navigator and click the Create button. Choose to build the data block manually, alter the Query Data Source Type property to 'Table', and enter the SELECT statement in the Query Data Source Name property. 。 Choose Tools -> Data Block Wizard, select Stored Procedure as the data source type, and base the block on the columns the tables. 。 Select the Data Blocks node in the Object Navigator and click the Create button. Choose to build the data block manually. Alter the Query Data Source Type to 'FROM' clause query', and enter the SELECT statement in the Query Data Source Name property.。
当线圈的匝数，电压不变时，电源频率增高，铁芯中磁通会（）。 减少。 增加。 不变。
You want to use the SQL Tuning Advisor to generate recommendations for badly written SQL statements in your development environment. Which three sources can you select for the advisor to analyze？（） Top SQL。 snapshots。 SQL Tuning sets。 index access path。 optimizer statistics。 materialized view log。
联合接地：使基站内建筑物的基础接地体和其他专设接地体相互连通形成一个共用地网，并将机房内设备的（）、保护接地以及建筑物防雷接地等共用一组接地系统的接地方式。 设备地。 馈线地。 天线接地。 工作接地。
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？（）
