选取节点 表达式 描述 nodename 选取此节点的所有子节点. / 从根节点选取. // 从匹配选择的当前节点选择文档中的节点,而不考虑它们的位置. . 选取当前节点. .. 选取当前节点的父节点. @ 选取属性. examples: 路径表达式 结果 bookstore 选取 bookstore 元素的所有子节点. /bookstore 选取根元素 bookstore. 注释:假如路径起始于正斜杠( / ),则此路径始终代表到某元素的绝对路径! bookstore/book 选取属于 bo…

http://www.postgresonline.com/journal/archives/131-Using-Recursive-Common-table-expressions-to-represent-Tree-structures.html Tree Problem and was based on PostgreSQL 7.4 technology. We'll repeat the text here for completeness and demonstrate the Pos…

WITH 允许在 SELECT 语句中定义"表"的表达式,这个"表"的表达式称之为"公共表表达式(Common Table Expression)",简称 CTE,仅在该 SELECT 语句范围内有效.CTE 的作用和临时表类似,CTE 的使用和 VIEW(视图) 类似,区别在于 CTE 不需要提前定义,VIEW 需要提前定义. SELETCT IN WITH 先来看一个例子: WITH regional_sales AS ( SELECT re…

子查询有时使用起来很麻烦,因为所有的过滤和匹配逻辑都必须集成到子查询表达式中.如果只需要执行一个任务,且只需要使用一次杳询表达式,子查询是很好的选择.但子查询不能被重用,也不能很好地支持多个需求.这个问题的一个常见解决方法是用子查询的内容填充一个临时表,连接和过滤表达式可以应用于这个临时表,但性能很差,且会消耗大量的系统资源,使用临时表还需要创建和使用另一个表的权限. CTE是这两个问题的最佳解决方法:它是一个只存在于内存的子查询,所以不需要特殊的权限,也不需要物理空间操作.CTE与传统的子查询…

https://stackoverflow.com/questions/30045871/sorting-the-view-based-on-frequency-in-sql-server Just like in sub queries, you can't use ORDER BY in a view definition in sql server unless you also use TOP. The reason for this is that Views are acted up…

Link:http://testautomationnoob.blogspot.com/2012/10/soapui-properties-and-property-related.html soapUI: Properties   I wanted to jump into a survey of the various test steps in this post, but quickly realized that an explanation of properties was nec…

前言 抓取网页数据时使用HtmlAgilityPack分析,需要通过xpath定位页面元素.如果有个xpath的生成和验证工具就事半功倍了,火狐浏览器插件FirePath配合Firebug就能完美实现. FirePath介绍如下: FirePath is a Firebug extension that adds a development tool to edit, inspect and generate XPath 1.0 expressions, CSS 3 selectors and…

(Sorry for that click-bait heading. Couldn’t resist ;-) ) We’re on a mission. To teach you SQL. But mostly, we want to teach you how to appreciate SQL. You’ll love it! Getting SQL right or wrong shouldn’t be about that You’re-Doing-It-Wrong™ attitude…

http://goessner.net/articles/JsonPath/ [edit] [comment] [remove] |2007-02-21| e1 # JSONPath - XPath for JSON A frequently emphasized advantage of XML is the availability of plenty tools to analyse, transform and selectively extract data out of XML do…

1. Parsing XML 1.1. XmlParser and XmlSlurper The most commonly used approach for parsing XML with Groovy is to use one of: groovy.util.XmlParser groovy.util.XmlSlurper Both have the same approach to parse an xml. Both come with a bunch of overloaded…