题目内容

安全可靠性是设备对生产安全的保障性能，即设备应具有必要的安全防护（），能避免在操作不当时发生重大事故。

A. 措施与说明
B. 规定并告知
C. 设计与装置
D. 规定与说明

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On your Oracle Database, you issue the following commands to create indexes: SQL > CREATE INDEX oe.ord_customer_ix1 ON oe.orders (customer_id, sales_rep_id) INVISIBLE; SQL> CREATE BITMAP INDEX oe.ord_customer_ix2 ON oe.orders (customer_id, sales_rep_id); Which two statements are true?（）

A. Only the ORD_CUSTOMER_IX1 index created.
Both the indexes are updated when a row is inserted, updated, or deleted in the ORDERS table.
C. Both the indexes are created: however, only ORD_CUSTOMERS_IX1 is used by the optimizer for queries on the ORDERS table.
D. The ORD_CUSTOMER_IX1 index is not used by the optimizer even when the OPTIMIZER_USE_INVISIBLE_INDEXES parameters is set to true.
E. Both the indexes are created and used by the optimizer for queries on the ORDERS table.
F. Both the indexes are created: however, only ORD_CUSTOMERS_IX2 is used by the optimizer for queries on the ORDERS table.

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