Tag：Definition
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Time：2020-4-2
This time, a user login permission control module is added to the original apitemplate project to verify how to abstract and support future expansion when facing some simple problems. The user login authority control module looks very simple, but its spare time is always limited. So take advantage of this opportunity to practice a user […]
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Time：2020-4-1
Check constraint A check constraint is the most common constraint type CREATE TABLE products ( product_no integer, name text, price numeric CHECK (price > 0) ); You can also give the constraint a separate name, which makes the error message clearer, or you can directly reference the constraint when you need to modify it CREATE […]
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Time：2020-4-1
Shell, commonly known as shell, is a Linux command and a programming language, which has many syntaxSH, as we often say, is generally only bash, that is, Bourne again shell, which is widely used in daily work due to its ease of use and free of charge. Bash is also the default shell for most […]
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Time：2020-3-31
Update time – 16:15, March 20, 2017;Update content – date format sample output, thank youGod’s favored oneCorrect errors in printing Pipe in angular 2 has the same function as filter in angular 1. X. They are used to process the input data, such as case conversion, value and date formatting. Angular 2 built in pipeline […]
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Time：2020-3-31
background JS due to the defects of language design (insufficient time limit?) There are some magical features. Beginners may be full of black question marks when they encounter them. Today, I’d like to introduce one of them: hoisting. If you are a JS novice, sometimes you will encounterundefinedperhapsReferenceErrorsWrong, and claiming ascension may be the culprit. […]
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Time：2020-3-31
Preface Because each version of ESS has some differences in function, this article introduces its function and use in 12.1.3. What is ess? The full name of ESS is Oracle Enterprise scheduler, which is a scheduled scheduling product of Oracle. How to use it? The common use of ESS is divided into three steps: defining […]
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Time：2020-3-30
judge C languageNonzeroandNot emptyThe value of is assumed to betrue, putZeroornullPresumed to befalse。 Here is the general form of a typical judgment structure in most programming languages: Judgement sentence C language provides the following types of judgment statements. Click on the link to see the details of each type. Sentence describe If statement OneIf statementConsists […]
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Time：2020-3-30
outline data base SQL operation ORM Practice data base data baseContainRelational typeDatabase andNon relationalDatabase.Relational: SQLite, mysql, Oracle, sqlserver, etc.Non relational: HBase, monogodb, elasticsearch, redis, etc.What we’re going to talk about today is the operation of relational databases. Relational databaseDatabase: contains multiple data tables.Data table: includes record in row and field in column.Column field: represents a […]
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Time：2020-3-30
Read the latest tutorial of angular 6 / rxjs, please visit the front-end fairy Road TemplateRef Before introducing templateref, let’s take a look at the HTML template element – < template >. Template elements are a mechanism that allows you to include client-side content that does not render when the page is loaded, but can […]
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Time：2020-3-29
Functions related to shipment in order of SAP SD basic knowledge I 1、 Shipping point determination Each order line item will determine a shipping point; the system will automatically bring out a shipping point, which you can modify within a limited range. Shipping point depends on a combination of three […]
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Time：2020-3-27
Graphql is an API query language, and also a runtime used to implement data query. It is different from the traditional restful mode. The data to be returned by the back end can be controlled by the front end. History of graphql Graphql core knowledge Graphql small actual combat Original address, welcome to star and […]
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Time：2020-3-26
Blog Homepage The previous chapter has explained string, set, operator overloading and so on. Next, it introduces the core foundation of closure, process control, method, class and so on. closure A closure is a method that represents a block of code that can be executed, and a closure is an object that can pass parameters […]
