Given an absolute path for a file (Unix-style), simplify it.
For example,
path = "/home/", => "/home"
path = "/a/./b/../../c/", => "/c"
click to show corner cases.
Corne...
1001
求个绝对值比较大小喽
1002
把字符串出现的字母记录一下，然后遍历a-z，谁第一个没出现就输出谁
1003
Problem Statement
We have N sticks with negligible thickness. The length of the i-th stick is ...
## 嵌套子查询subquery
**单行子查询**
select select_list
from table
where expr operator
(select select_list from table);
operator includes a comparison condition such as >, =, or IN
如：
select la...
## Hierarchical Retrieval 层次检索
you should be able to:
1、Interpret the concept of a hierarchical query
2、Create a tree-structured report
3、Format hierarchical data
4、Exclude branches from the t...
## Retrieving Data by Using Subqueries 子查询
you should be able to:
1、Write a multiple-column subquery 多列子查询
2、Use scalar subqueries in SQL 标量子查询
3、Solve problems with correlated subq...
远程登录
conn hr/hr@192.168.133.117:1521/orcl l
SQL->a where id=1 不换行进行语句追加
SQL->c /whree/where 修改语句
SQL->r 执行
清空buff
clear buff
删除行号
del 行号
del 5
删除多行
del 行...
## Manipulating Data 数据操作
you should be able to:
1、Specify explicit default values in the INSERT and UPDATE statements
2、Describe the features of multitable INSERTs
3、Use the following types of...
## Generating Reports by Grouping Related Data使用分组生成报告
you should be able to use the:
1、ROLLUP operation to produce subtotal values
2、CUBE operation to produce cross-tabulation values
3、GR...
## Managing Schema Objects管理模式对象
you should be able to:
1、Manage constraints
2、Create and use temporary tables
3、Create and use external tables
Use the ALTER TABLE statement to:
1、Add or...
