• Hive function — windowing function 1


    Windowing function First acquaintance Window: the range of datasets that the function evaluates at run timeFunction: running function! Only the following functions are supported: Windowing functions: LEAD: LEAD (scalar_ Expression [, offset] [, default]): returns the column value of the specified column of the following n rows of the current row! If not found, the […]

  • Analysis of the underlying operation principle of SQL query


    SQL language everywhere。 SQL is not only the exclusive skill of technical personnel, it seems that everyone can write SQL, just as everyone is a product manager. If you do background development, crud is a routine. If you do data warehouse development, writing SQL may occupy most of your working time. When we understand the […]

  • SQL Foundation


    SQL User table id pwd name 0 123 gan 1 123 gan 3 12 peng Book table Bname aUtherId catagory mathematics 1 tool chinese 0 literature English 2 language Select extracts data from the database select * from user select user.id from user The distinct keyword selects a unique different value select distinct user.name from […]

  • Query optimization of MySQL


    Reference website:http://www.liyblog.top/p/6Here is a summary of 52 SQL query optimization, let’s take a detailed look, hope to help you 1. To optimize the query, we should try to avoid full table scanning. First, we should consider building indexes on the columns involved in where and order by. 2. We should try to avoid judging the […]

  • Notes of C + + primer Chapter 5 sentences


    An empty block is equivalent to an empty statement. The case tag must be an integer constant expression, and default is also a special case tag. Tags should not appear alone, it must be followed by a statement or another case tag. If a variable with an initial value is outside the scope somewhere and […]

  • Three steps of SQL optimization


    One day, the development students reported that there was a very full SQL in the online business database, and it took almost one minute to finish each time. I hope we can help optimize it. The specific SQL is as follows: SQL optimization step 1 – view execution plan For a SQL optimization, our first […]

  • Record 30 methods of optimizing SQL query in MySQL


    1. To optimize the query, we should try to avoid full table scanning. First, we should consider building indexes on the columns involved in where and order by. 2. Avoid using in where clause as far as possible= Or < > operator, otherwise the engine will give up using the index and scan the whole […]

  • Ant Design blazor, another powerful tool for client web development based on. Net


    Hello, I’m dotnet9. Following the introduction of bootstrap style blazor UI component library in the last article, today I’d like to introduce another blazor UI component library: an enterprise component library based on Ant Design and blazor. This article navigation: 1、 About ant design blazor 2、 Ant Design blazor’s community contribution 2.1 project attention 2.2 […]

  • In the name of AI, “Ai” is installed in the contract management of tens of millions of levels. Huawei’s business managers have a lot of work to do!


    Abstract: can AI be used to improve the efficiency of contract management? Huawei has submitted a textbook level answer sheet with its own AI practice. For the business elites of enterprises, what makes them both “suffering” and “happy”, both “hard to sleep” and “high spirited”? The answer is to sign a contract. Almost every enterprise […]

  • MySQL Foundation: select query statement


    blog:https://www.cnblogs.com/Rohn/ catalog summary Grammatical format Database case Common grammar Use * to query all the contents of the table Grammatical format example The fields specified in the query table Grammatical format example Filtering duplicate data Grammatical format example Set alias Table alias Grammatical format example field alias Grammatical format Limit the number of records of […]

  • C # advanced chapter


    preface Reminder: in order to learn knowledge more thoroughly Remember more firmly, I will write down the knowledge through the way of teaching explanation, because in the process, people will change from students to teachers. This process will dig out new knowledge and ideas. It is a process of deep excavation and improvement of knowledge […]

  • Basic summary of orcla (2)


    Set operator Notes on using set operator Column names and expressions in the select list should correspond to * * quantity and data type * * Parentheses can change the order of execution Order by clause: Can only appear at the end of a statement You can use the column name, alias, or relative position […]