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C# in parameter modifier

In modifier record: The new version of C # adds an in modifier: to ensure that the data sent to the method is not changed (value type), when the in modifier is used to refer to the type, the content of the variable can be changed, but the variable itself cannot be changed. Personal Understanding: In modifier transfers data that is read-only in the method and cannot be changed at all. class Program { static void Main(string[] args) { int x = 25; ChangeX(x); } private...

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Judging whether there is data in time interval by SQL

There is a problem in the project. Users need to get the data of the current month or months, but there is a requirement that if there is already a list that contains the data of these months, then duplicate data can not be extracted. In fact, after I finished my way of doing this, I found that there are two ways. The first one is to add identification bits to the acquired data. If the data has been occupied by the documents, it should be excluded according to the identification at the time of extraction. This method should take into...

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The Differences and Differences between MySQL and Oracle

I. The similarities between MySQL and Oracle: 1. All are relational database management systems (MySQL open source) 2. They are all popular databases (Oracle takes distributed as its core). Second, MySQL and Oracle have their own characteristics: 1. Oracle’s own characteristics: (1) Complete data management functions: 1) The large amount of data; 2) the persistence of data preservation; 3) Data sharing; 4) Reliability of data; (2) Complete relationship products: 1) Information Criterion – All information in relational DBMS...

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Five steps for Ajax requests

Create an XMLHttpRequest asynchronous object var xhr = new XMLHttpRequest() Setting callback function xhr.onreadystatechange = callback Connecting with Server by Open Method // get mode xhr.open("get", "test.php", true) // Sending data by post requires setting the request header xhr.open("post", "test.php", true) xhr.setRequestHeader("Content-Type", "application/x-www-form-urlencoded") Send data to the server // get does not need to pass parameters xhr.send(null) // Post needs to pass...