OCP-1Z0-053-V12.02-464题

464.Which of the following are valid settings for the NLS_COMP parameter? (Choose all that apply.)

A. ASCII

B. ANSI

C. BINARY

D. MONOLINGUAL

E. MULTILINGUAL

Answer: BC

答案解析：

参考：http://docs.oracle.com/cd/E11882_01/server.112/e40402/initparams145.htm#REFRN10117

NLS_COMP specifies the collation behavior of the database session.

Values:

• BINARY

  Normally, comparisons in the WHERE clause and in PL/SQL blocks is binary unless you specify the NLSSORT function.

• LINGUISTIC

  Comparisons for all SQL operations in the WHERE clause and in PL/SQL blocks should use the linguistic sort specified in the NLS_SORT parameter. To improve the performance, you can also define a linguistic index on the column for which you want linguistic comparisons.

• ANSI

  A setting of ANSI is for backwards compatibility; in general, you should set NLS_COMP to LINGUISTIC

Note:

Unless you explicitly set the value for NLS_COMP in your initialization parameter file, a default value of NULL is shown in the following views: V$PARAMETER, V$SYSTEM_PARAMETER, V$PARAMETER2, V$SYSTEM_PARAMETER2, and NLS_INSTANCE_PARAMETERS. However, the actual default value, and behavior, is BINARY. Note that you cannot change the default to NULL, because NULL is not among the valid values.

Note:

The value of this initialization parameter NLS_COMP is used to initialize the session value of this parameter, which is the actual value referenced by the SQL query processing. This initial value is overridden by a client-side value if the client uses the Oracle JDBC driver or if the client is OCI-based and the NLS_LANG client setting (environment variable) is defined. The initialization parameter value is, therefore, usually ignored.