RECURSIVE 前言 CTE or WITH 在WITH中使用数据修改语句 WITH使用注意事项 RECURSIVE 递归查询的过程 拆解下执行的过程 1.执行非递归部分 2.执行递归部分,如果是UNION,要用当前查询的结果和上一个working table的结果进行去重,然后放到到临时表中.然后把working table的数据替换成临时表里面的数据. 3.同2,直到数据表中没有数据. 4.结束递归,将前几个步骤的结果集合并,即得到最终的WITH RECURSIVE的结果集 WITH R
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
This is the last in a series of Postgres posts that Pat Shaughnessy wrote based on his presentation at the Barcelona Ruby Conference. You can also watch the video recording of the presentation. The series was originally published on his personal blog
https://coderwall.com/p/whf3-a/hierarchical-data-in-postgres ------------------------------------------------------------------------------- This tip will try to answer the following questions: How can we represent a tree of data in postgres How can
本文实例讲述了ASP.NET利用第三方类库Newtonsoft.Json提取多层嵌套json数据的方法,具体例子如下. 假设需要提取的json字符串如下: {"name":"lily","age":23,"addr":{"city":guangzhou,"province":guangdong}} 先引用命名空间: using Newtonsoft.Json; using Newtons
postgres创建索引参考 http://www.cnblogs.com/stephen-liu74/archive/2012/05/09/2298182.html CREATE TABLE test1 ( id integer, content varchar ); CREATE INDEX test1_id_index ON test1 (id); 创建存储过程 CREATE OR REPLACE FUNCTION update_sqs(lng "v
在测试环境中使用某个账号ESCMOWNER对数据库进行ALTER操作时,老是报如下错误: ORA-00604: error occurred at recursive SQL level 1 ORA-20016: (ALTER) Action denied as it is a protected object! ORA-06512: at line 7 不清楚发生了什么情况,于是想跟踪当前会话,查看具体原因,查看当前会话的SID为967 SELECT USERENV('SID') FROM D
在scala中如果一个函数在最后一步调用自己(必须完全调用自己,不能加其他额外运算子),那么在scala中会复用函数栈,这样递归调用就转化成了线性的调用,效率大大的提高.If a function calls itself as its last action, the function's stack frame can be reused. This is called tail recursion.=> Tail recursive functions are iterative proc
