【图解设计模式】Abstract Factory模式
抽象工厂将抽象零件组装为抽象产品。
示例将带有层次关系的链接的集合制作成HTML文件。
类图
Item类1234567891011package factory;public abstract class Item { protected String caption; pub
...
【SQL进阶教程】CASE表达式
Posted on
|
In
SQL
CASE表达式概述CASE表达式有简单CASE表达式(simple case expression)和搜索CASE表达式(searched case expression)两种写法。在编写SQL语句的时候需要注意，在发现为真的WHEN子句时，CASE表达式的真假值判断就会中止，而剩余的WHEN子句会
...
【SQL基础教程】GROUPING运算符
Posted on
|
In
SQL
同时得到合计行如果想要获得同时得出小计和合计的结果，通常的做法是分别计算出合计行和按照商品种类进行汇总的结果，然后通过UNION ALL连接在一起。
123456SELECT '合计' AS product_type, SUM(sale_price)FROM ProductUNION ALLSELE
...
【SQL基础教程】窗口函数
Posted on
|
In
SQL
什么是窗口函数窗口函数也称为OLAP函数。OLAP是Online Analytical Processing的简称，意思是对数据库数据进行实时分析处理。例如，市场分析、创建财务报表、创建计划等日常性商务工作。窗口函数就是为了实现OLAP而添加的标准SQL功能。
窗口函数的语法1<窗口函数>
...
[LeetCode] Problem 599 - Minimum Index Sum of Two Lists
Suppose Andy and Doris want to choose a restaurant for dinner, and they both have a list of favorite restaurants represented by strings.
You need to h
...
[LeetCode] Problem 863 - All Nodes Distance K in Binary Tree
We are given a binary tree (with root node root), a target node, and an integer value K.
Return a list of the values of all nodes that have a distance
...
[LeetCode] Problem 4 - Median of Two Sorted Arrays
There are two sorted arrays nums1 and nums2 of size m and n respectively.
Find the median of the two sorted arrays. The overall run time complexity sh
...
[LeetCode] Problem 480 - Sliding Window Median
Median is the middle value in an ordered integer list. If the size of the list is even, there is no middle value. So the median is the mean of the two
...
[LeetCode] Problem 239 - Sliding Window Maximum
Given an array nums, there is a sliding window of size k which is moving from the very left of the array to the very right. You can only see the k num
...
[LeetCode] Problem 57 - Insert Interval
Given a set of non-overlapping intervals, insert a new interval into the intervals (merge if necessary).
You may assume that the intervals were initia
...