q3.which statement is true regarding external tables
a. the default reject limit for external tables is unlimited.
b. the data and metadata for an external table are stored outside the database.
c.oracle_loader and oracle_datapump have exactly the same functionality when used with an external table.
d. the create table as select statement can be used to upload data into regular table in the database from an external table.
correct answer: d
explanation/reference:
本题解释：
a 选项错误的原因是，该子句的默认值是 0 而不是无限；
b 错误是因为源数据是应存在于中；
c 错误是因为他们的功能不一样，一个是 load 时用，一个是 unload 时用；
d create table as select语句可用于将数据从外部表中装载到数据库中的常规表中。