oracle------drop user user_name[cascade]

1:drop user user_name;
若该用户下无任何表或者视图。。则删除该用户。。否则会提示加cascade字段。
2:drop user user_name cascade;
还删除该用户名下的所有表和视图。
详细说明如下:
 

user
Specify the user to be dropped. Oracle Database does not drop users whose schemas contain objects unless you specify CASCADE or unless you first explicitly drop the user's objects.
CASCADE
Specify CASCADE to drop all objects in the user's schema before dropping the user. You must specify this clause to drop a user whose schema contains any objects.
1 If the user's schema contains tables, then Oracle Database drops the tables and automatically drops any referential integrity constraints on tables in other schemas that refer to primary and unique keys on these tables.
2 If this clause results in tables being dropped, then the database also drops all domain indexes created on columns of those tables and invokes appropriate drop routines.
3 Oracle Database invalidates, but does not drop, the following objects in other schemas:
  #Views or synonyms for objects in the dropped user's schema
  # Stored procedures, functions, or packagthat  query             objects    in the dropped user's schema
4 Oracle Database does not drop materialized views in other schemas that are based on tables in the dropped user's schema. However, because the base tables no longer exist, the materialized views in the other schemas can no longer be refreshed.
5 Oracle Database drops all triggers in the user


作者: jennyljd   发布时间: 2010-11-28