Tag:The Works of Liezi

  • Conditional judgment and process control of Linux shell programming


    1、 Conditional sentence 1.1 judge by document type Two judgment formats: test -e /root/install.log [-e /root/install.log]//Recommend 1.2 judging by file authority 1.3 comparison between two documents 1.4 comparison between two integers 1.5 string judgment 1.6 multiple condition judgment 2、 If statement 2.1 single branch if statement Column 1: judge whether the current login user isroot […]

  • Encryption and decryption of react URL parameters


    React web project encryption histoy is the route parameter of browserrouter Using JS method btoa and decodeuricomponent Encryption: btoa (unescape (encoding component (markup))) Decryption: decodeuricom ponent (escape (window. Atob (markup))) The Works of Liezi: Page 1: parameter transfer var url=’name=1&id=2′; url=btoa(unescape(encodeURIComponent(url))) var newUrl='[http://baidu.com?$]${url}’ window.open(newUrl) Page 2: receiving parameters var url=this.props.location.search; url=url.substring(1) var newUrl=decodeURIComponent(escape(window.atob(url))) const {name,id}=queryString.parse(newUrl)

  • Oracle (day 5)


    Subquery 1. Single line subquery: For example: select * from EMP where Sal > (select Sal from EMP where ename =’allen ‘); 2. Multi row subquery: any all in Greater than any is greater than the minimum   select * from emp where sal>any(select sal from emp where deptno=10);   select * from emp where sal>(select min(sal) […]

  • Sub query of MySQL


    Meaning:The select statement appearing in other statements is called sub query or internal query, and the external query statement is called main query or external query. Classification:By subquery location: After select: Only scalar subqueries are supported Behind from Support table subquery Behind where or having scalar subquery Column query Row subquery After exists (related subqueries) […]