• Introduction to the use of with as in SQL Server


    1、 The meaning of with as With as phrase, also known as subquery factoring, allows you to do a lot of things and define a SQL fragment that will be used by the entire SQL statement. Sometimes, it is to make the SQL statement more readable, or it may be in different parts of union […]

  • SQL server queries tree structure through with as method


    1、 With as common table expression It is similar to view, but does not create an object. With as common table expression does not create an object and can only be followed by a select statement 1. Realize recursive query (tree structure) 2. The common table expression can be referenced multiple times in a statement […]

  • Analysis of python with tag usage


    This article mainly introduces the use of python with tag parsing, the article through the example code is very detailed, for everyone’s study or work has a certain reference learning value, need friends can refer to 1. In Python DTL template, if you want to define variables, you can use the “with” statement. 2. There […]

  • Fix MAC brew installation mongodb error: no available formula with the name ‘mongodb’


    According to the official explanation of homebrew, mongodb is no longer open source and has been removed from homebrew It is because the commercialization of mongodb is not ideal, so it chooses closed source. Therefore, the brew installation methods before the source is closed will report errors. Many articles on the Internet are based on […]

  • Vscode add open with code to open the folder by right click


    Problem description Because I didn’t pay attention to the detailed reading tips when installing vscode, and the first installation was quite casual. I just wanted to try vscode before installation, so I missed the very easy function of checking open with code during installation!!! How did I find out? It’s because I’ve been studying recently […]

  • Recursive with subquery method of Oracle 11gr2


    Next, I will introduce the recursive with subquery method of Oracle 11gr2 in detail, as follows: SQL> with emp_data(ename,empno,mgr,l) as (select ename, empno, mgr, 1 lvl from emp where mgr is null union all select emp.ename, emp.empno, emp.mgr, ed.l+1 from emp, emp_data ed where emp.mgr = ed.empno ) SEARCH DEPTH FIRST BY ename SET order_by […]

  • Use of Python async with and async for


    There are few Chinese materials about async with and for online. I will translate the official statement of PEP 492. Async with Async Context Manager Asynchronous context manager refers to a context manager that can pause execution at the enter and exit methods. In order to achieve this function, two new methods need to be […]

  • Use of Oracle Recursive Query Start with Connect by Prior


    I. Basic Grammar The basic syntax of connect by recursive query is: Select 1 from table start with… connect by prior id = pId Start with: Represents what is the root node, unrestricted can write 1 = 1, to the ID of 123 nodes as the root node, write as start with id = 123 […]

  • The Method of Using with to Realize Recursion in SQL Server 2005


    Copy codeThe code is as follows: WITH fw_requestion_note_temp (old_apply_id) AS (– Put the root node into the temporary tableSELECT old_apply_id FROM fw_requestion_note –WHERE old_apply_id = ‘e741470e-8b5c-4f91-9b03-c7474d103aef’ Recursively retrieve the data of its byte points based on the data already retrieved  UNION ALL SELECT fw.old_apply_id FROM fw_requestion_note fw  INNER JOIN fw_requestion_note_temp temp ON fw.apply_id = temp.old_apply_id […]