SQL UNION 操作符 UNION 操作符用于合并两个或多个 SELECT 语句的结果集。 请注意，UNION 内部的 SELECT 语句必须拥有相同数量的列。列也必须拥有相似的数据类型。同时，每条 SELECT 语句中的列的顺序必须相同。 SQL UNION 语法SELECT column_name(s) FROM table_name1 UNION SELECT column_name(s) FROM table_name2 注释： 默认地，UNION 操作符选取不同的值。如果允许重复的值，请使用 UNION ALL。 SQL UNION ALL 语法SELECT column_name(s) FROM table_name1 UNION ALL SELECT column_name(s) FROM table_name2 另外，UNION 结果集中的列名总是等于 UNION 中第一个 SELECT 语句中的列名。 下面的例子中使用的原始表：Employees_China: E_ID E_Name 01 Zhang, Hua 02 Wang, Wei 03 Carter, Thomas 04 Yang, Ming Employees_USA: E_ID E_Name 01 Adams, John 02 Bush, George 03 Carter, Thomas 04 Gates, Bill 使用 UNION 命令实例 列出所有在中国和美国的不同的雇员名： SELECT E_Name FROM Employees_China UNION SELECT E_Name FROM Employees_USA 结果 E_Name Zhang, Hua Wang, Wei Carter, Thomas Yang, Ming Adams, John Bush, George Gates, Bill 注释： 这个命令无法列出在中国和美国的所有雇员。在上面的例子中，我们有两个名字相同的雇员，他们当中只有一个人被列出来了。UNION 命令只会选取不同的值。 UNION ALL UNION ALL 命令和 UNION 命令几乎是等效的，不过 UNION ALL 命令会列出所有的值。 SQL Statement 1 UNION ALL SQL Statement 2 使用 UNION ALL 命令实例： 列出在中国和美国的所有的雇员： SELECT E_Name FROM Employees_China UNION ALL SELECT E_Name FROM Employees_USA 结果 E_Name Zhang, Hua Wang, Wei Carter, Thomas Yang, Ming Adams, John Bush, George Carter, Thomas Gates, Bill
Merge Computes a geometric union of the input features. All features and their attributes will be written to the output feature class. ArcToolbox--Data Management --General--Merge Union Computes a geometric union of the Input Features. All features will be written to the Output Feature Class with the attributes from the Input Features, which it overlaps. ArcToolbox--Analysis--Overlay--Union 举个例子 。有两个面，面 A 和面 B ，这两个面不一定要相邻。选中两个面后，如果用 Union ，则产生一个新的面要素，即为面 A 和面 B 的集合，而原来的面 A 和面 B 依然保留。如果用 Merge 也产生一个新的要素，几何形体依然为面 A 和面 B 的集合，即面 C ，但它的属性只能从 A 和 B 中选择一个，也就是说属性合并。而且原来的面 A 和面 B 也就不存在了。另外，无论是 Union 还是 Merge 在合并的时间，必须选择同一种几何类型，如面与面合并，线与线合并。 认真体会： Merge_management ， Union_analysis 。 附 上练习数据及代码（ Practice.rar ）。 参考文献 arcgis 中 union 、 merge 、 append 和 intersect 区别 . ArcGIS 中各种合并要素（ Union 、 Merge 、 Append 、 Dissolve ）的异同点分析 . ArcGIS 中各种合并要素（ Union 、 Merge 、 Append 、 Dissolve ）的异同点分析 . Toolbox 中的 dissolve 工具以及与排序工具的组合使用 .
胡焕庸线：更多的卫星图片 （1） Figure 2. (a) Solar-induced chlorophyll fluorescence (SIF) as retrieved from GOSAT from June 2009 to December 2011. (b) Modeled gross primary production (GPP) for the same time period and locations. 3, 4 GOSAT: Global Greenhouse Gas Observation by Satellite. sr: Steradian. MPI-BGC: Max Planck Institute for Biogeochemistry. Figure 2 shows a global average of SIF as well as a corresponding map of modeled GPP, revealing strong correlations between both parameters. 8 These observations are directly linked to photosynthesis, provide new information not available from greenness indices, and enable an entirely new perspective on the global carbon cycle. Observations of SIF can, therefore, have an important role in carbon cycle research and alleviate the large uncertainties in GPP measurements. （2） Figure 1. (a) Global map of plant chlorophyll fluorescence as measured by the GOSAT satellite from June 2009 to May 2010. The fluorescence is measured at a spectral wavelength of 757 nanometers and superimposed on a 2°x 2° grid. Areas of higher and lower plant activity can be seen in different parts of the world. (b) Time variations in the fluorescence signal given off by vegetation, from June 2009 to August 2010. A pronounced seasonal variation can be seen that reflects the growing season in the northern hemisphere and seasonal vegetation shifts in the tropics. 相关链接： 2014-12-24，胡焕庸线：清晰可见（美国极轨道碳观测者卫星2号OCO-2的荧光图） http://blog.sciencenet.cn/blog-107667-853546.html Christian Frankenberg, Joseph Berry, Luis Guanter and Joanna Joiner, 15 February 2013, Remote sensing of terrestrial chlorophyll fluorescence from space. http://spie.org/x92267.xml Amber Jenkins, Jet Propulsion Laboratory, February 29, 2012, Watching the planet breathe http://climatesciences.jpl.nasa.gov/news-release/2012-02-earth-breathe
胡焕庸线：清晰可见 （美国极轨道碳观测者卫星2号OCO-2的荧光图） 不久前American Geophysical Union 发布了 (pictured, with data averaged from August to October of this year) as measured by the Orbitin g Carbon Observatory-2. The amount mopped up by plants during photosynthesis or released during respiration. Higher resolution fluorescence mapping could one day be used to help assess crop yields and how they respond to drought and heat in a changing climate. 从这张图上，可以清晰地看到胡焕庸线：植物生长的情况，可以在二氧化碳荧光图上清晰可见。 图片来自：Satellite captures glowing plants from space http://news.sciencemag.org/climate/2014/12/satellite-captures-glowing-plants-space （1）全球 （2）中国的局部图 （3）胡焕庸线 卫星从太空捕获了植物所发的光芒（ 赵斌 老师翻译） 阳光照射在植物上，其中约有1%会再发射出来，形成一种微弱的荧光，这可以作为光合作用活动的一种度量。在今天的美国地球物理学会会议上，科学家公布了一幅由极轨道碳观测者卫星2号(OCO-2)获取的荧光图（如图，数据来源于今年8~10月的平均值）。 NASA的这颗卫星于今天7月份发射，其目的是绘制大气中净含碳总量。但这幅荧光图，则是利用其意外的辅助功能，提供了一种更为直观的碳通量测量方法：植物在进行光合作用时所消耗的量或呼吸作用时所释放的量。这些发现将帮助科学家解开一些诸如亚马逊雨林的地区究竟是碳吸收还是碳排放的问题，因为那里的森林砍伐可能导致巨大的碳排放，而光合作用也可能形成非常高的碳汇。这幅图揭示出，赤道附近的热带雨林正在活跃地吸收碳，而美国东部的玉米带在生长季末仍然是一个碳汇。 有朝一日，高分辨荧光地图还可帮助评估作物产量，以及在变化的气候中它们如何适应干旱和炎热。 相关链接： 中国科学报，2014-12-23，美卫星成功捕捉植物碳汇 http://news.sciencenet.cn/htmlnews/2014/12/309847.shtm Eric Hand, 2014-12-18, Satellite captures glowing plants from space http://news.sciencemag.org/climate/2014/12/satellite-captures-glowing-plants-space 王铮，2014-12-02，胡焕庸线的稳定性及其突破 精选 http://blog.sciencenet.cn/blog-2211-847928.html 王铮，2014-12-11，再说胡焕庸线 精选 http://blog.sciencenet.cn/blog-2211-850151.html 王铮，2014-12-14，关于胡焕庸线研究的七篇文章及关 于胡焕庸线的“破线”问 题 http://blog.sciencenet.cn/blog-2211-850852.html 李小文，2014-12-05，【地图之问】关于胡焕庸线答博友 精选 http://blog.sciencenet.cn/blog-2984-848586.html 胡焕庸线（百度百科） http://baike.baidu.com/view/1269078.htm 黑河-腾冲线（wiki百科） http://en.wikipedia.org/wiki/Heihe%E2%80%93Tengchong_Line
Ok, they at least have invaded Hawaii, the 50th state of the US. I only checked the balance today, and was warned that there may be a service charge by the Chinese bank. Does anyone know how much Bank of China may charge for such an inquire?
You may have heard of open access publications. Many new journals are following this new model, in which anyone with an internet connection can download an article free of charge. In this model, the costs of publication are generally paid by the author of the article. In Europe, the open access system has just gained a big boost. The European Union (EU) has pushed to see that all EU-funded research be made available free of charge to its citizens. The open access model most easily accomplishes this. In fact, the European Commission launched 'OpenAIRE' (Open Access Infrastructure for Research in Europe). This system will eventually allow all Europeans to access all EU-funded research material. It will also promote the open access model worldwide. http://europa.eu/rapid/pressReleasesAction.do?reference=IP/10/1644format=HTMLaged=0language=ENguiLanguage=en
标签: Union
