701题求解

显示全部楼层 · 2005-1-11 10:46:00

which of the following can be exported?
A.indexs
B.trigger
C.user defined functions
D.tables with identity columns.
您觉得哪个是正确答案,为什么?

还有一题是:
how does db2 enforce table check constraints for data add to a table with the load utility?
A.with the build phase of the load
B.with the set integrity statement
C.with the delete phase of the load
D.with the update constraints statement

千问 · 2005-1-11 10:46:00

1选A,导出时先ixf时可以保留.
2.B,个人认为
希望大家讨论

千问 · 2005-1-11 10:46:00

第一题选D是不是更有道理呢?
理由是导出的是表而不是独立地导出索引,大家谈谈自己的看法啦.

千问 · 2005-1-11 10:46:00

导出成ixf格式可以保留索引和主键信息,
D指的是标识列,是导不出来的,
要不可以试试

千问 · 2005-1-11 10:46:00

终于找到第一题的答案了
Using export with identity columns
The export utility can be used to export data from a table containing an identity column. If the SELECT statement specified for the export operation is of the form "select * from tablename", and the METHOD option is not used, exporting identity column properties to IXF files is supported. The REPLACE_CREATE and the CREATE options of the IMPORT command can then be used to recreate the table, including its identity column properties. If such an IXF file is created from a table containing an identity column of type GENERATED ALWAYS, the only way that the data file can be successfully imported is to specify the identityignore modifier. Otherwise, all rows will be rejected (SQL3550W).

千问 · 2005-1-11 10:46:00

IXF (integrated exchange format, PC version), in which most of the table attributes, as well as any existing indexes, are saved in the IXF file, except when columns are specified in the SELECT statement. With this format, the table can be recreated, while with the other file formats, the table must already exist before data can be imported into it.

千问 · 2005-1-11 10:46:00

大虾们发表自己的看法啦.

千问 · 2005-1-11 10:46:00

呵~
总结一下,如果用ixf格式的话大多数表的属性(例如标识列)和索引可以一起导出
(这一点我实际试过了)
所以,应该先A
至于D.tables with identity columns.,它表述的意思可能是只有带标识列的表才可以导出?
比较模糊.