disadvantages of teleconferencing

In general, the HTTP protocol is a stateless service, and it does not save any user request information. Web applications have been greatly developed until Netscape began using cookies to save user request information. Now asp.net programmers can save user request information in a number of ways. Here are a few ways to ASP.net about client state management. asp.net, which provides cookies, querystrings (URL), Hidden fields, View State and control state (ASP.net 2.0), manages client requests.

with transaction semantics in bean code. In both cases, the container manages the transaction and determines whether the given transaction should be committed. 5, based on the components of the design. Entity beans are designed to contain components that are configured with deployment descriptors and can be deployed to any Java EE application Server without changing any code. In summary, the advantage of entity beans is that they can benefit from standardization and industry best practices, s

Stored Procedures | Encapsulation SQL Server 2005 can write stored procedures in. NET languages, so in small and medium applications, it becomes a good choice to use the stored procedure encapsulation application logic. The advantages of using stored procedures to encapsulate application logic are as follows: 1, Dba+developer Division of labor Clear. Code modularity between. Reduce database operator and programmer errors. 2. Database security; You can set the account in the connection string

; try {//Load Database driver Class.forName ("Com.mysql.jdbc.Driver"); Get the database link through the data-driven management class connection =drivermanager.getconnection ("Jdbc:mysql://localhost:3306/mybatisdata?characteren Coding=utf-8 "," root "," root "); Define SQL statements, where? Identity placeholder String sql = "SELECT * from user where id =?"; Get preprocessing statement preparedstatement = connection.preparestatement (sql); S

that the composite column length cannot be too long; In a composite index, all columns must be from the same table, and composite columns cannot be created across tables In a composite index, the order of the columns is very important, so the order of the columns is carefully arranged, in principle, the most unique column should be defined first, for example, the index on (col1,col2) is not the same as the index on (col2,col1), because the order of the two-indexed columns is different ; for the

composite index, the total length of the columns that make up the composite index cannot exceed 900 bytes, which means that the composite column length cannot be too long; In a composite index, all columns must be from the same table, and composite columns cannot be created across tables In a composite index, the order of the columns is very important, so the order of the columns is carefully arranged, in principle, the most unique column should be defined first, for example, the index on (col1

Summary of advantages and disadvantages of ORACLE five tables:1, Normal table (heap table): Suitable for most design scenarios, there are advantages and disadvantages.Advantages:A, the syntax is simple and convenientb, suitable for most scenesDisadvantages:A, the update log cost is largeB,delete Cannot free space (HWM high water mark does not drop)C, table record too large retrieval too slowD, index back table read overheadE, even if inserted in order

the gender column of the personnel table, in the results of the query, the data rows of the result set occupy a large proportion of the data rows in the table, that is, the data rows that need to be searched in the table are large. Increasing the index does not significantly speed up the retrieval. Third, for those columns defined as text, the image and bit data types should not be indexed. This is because the amount of data in these columns is either quite large or has very little value. The i

the form of a two-dimensional table! a two-dimensional table is made up of rows and columns, knowing that the row and column numbers will be able to locate the data in the table! Excel is a two-dimensional table! Easy to use, the basic common SQL language makes it easy to operate relational databases! SQL is supported , so complex queries can be made! easy to maintain, rich integrity (domain integrity, entity integrity, referential integrity, and custom integrity) greatly reduces data redun

exceed 900 bytes, which means that the composite column length cannot be too long; In a composite index, all columns must be from the same table, and composite columns cannot be created across tables In a composite index, the order of the columns is important, so the order of the columns is carefully arranged, in principle, the most unique column should be defined first, for example, the index on (col1,col2) is not the same as the index on (col2,col1), because the order of the two-indexed colum

This article focuses on the details of Ajax, the origin of Ajax, the principle of Ajax, and the advantages and disadvantages of Ajax. Now let's see this article together. What is Ajax In fact, Ajax already belongs to the old technology, and now almost no one will use, here is mainly the bottom of the things to share with you, in case of loading the interviewer. Ajax, "Asynchronous JavaScript and XML" (Asynchronous JavaScript and XML), refers to a web

created, it waits for the first time to execute. At that time, the stored procedure was optimized, and the query plan was compiled and cached on the system. When you run the stored procedure several times, the cached query plan is used instead of creating a new query plan, unless specified by using the WITH RECOMPILE option. This means that each time the stored procedure is used, the stored procedure skips a lot of optimizations and compilation work. The exact time to save depends on the comple

version determines the stability of the RAC operation. It is important for database engineers and hardware engineers to have extensive environmental checks, validations, and extensive testing after deployment before installing the configuration.　　Second, high-performanceHigh performance is also a major headache for migrating from a single machine environment to a RAC environment, and RAC is not a high-performance solution. In the current hardware environment of gigabit Network, many times the s

complexity of the application index-ready file is O (n).C) Poll use Nfds to specify the maximum number of file descriptors and events to listen to, this number can reach the system agreed to open the largest file description of the descriptor. That is, 65535.D) can only work in the LT mode.3) Epoll:A) epoll the file Description descriptor and events of the user's booklet into the event table in the kernel. Provides a stand-alone system call Epoll_ctl to manage user events, and epoll the way cal

Label:The benefits of a relational database:1. Maintain data consistency (transaction processing)2. Due to standardization, the cost of updating data is small (the same fields are basically only one place)3. Complex queries such as joins can be madeOne of the best advantages of relational databases is the ability to maintain data consistency.The lack of a relational database:Not good at handling1. Write processing of large amounts of data2. Index or table structure (schema) changes for tables wi

Introduction: DB2 9 databaseIt is an important development in the development history of DB2 databases, but DB2 9 databases are not perfect, so there are both good and bad aspects, the following describes the advantages and disadvantages of the DB2 9 database. Compared with other database management systems, DB2 9 has made significant innovations. In fact, DB2 9's support for XML is not only reflected in XML data, but also can be used to solve some pr

The advantages and disadvantages of Oracle Database indexes are mdash, mdash, and learning notes. The main advantage is convenient query and improved system performance. By creating a unique index, you can ensure that the database The advantages and disadvantages of Oracle Database indexes are mdash, mdash, and learning notes. The main advantage is convenient query and improved system performance. By creat

ASP. NET common data binding control advantages and disadvantages Analysis SummaryThe purpose of this article is to make an overview of ASP. NET data-bound control, mainly analyze the advantages and disadvantages of various data-bound controls, so as to choose the appropriate control for data binding in the actual development to improve the development efficiency.Because most of these data-bound controls ar

What are the advantages and disadvantages of single and multi-entry PHPframework? What are the advantages and disadvantages of the single portal and multi-portal of PHP framework? Reply content: What are the advantages and disadvantages of the single portal and multi-portal of PHP framework? The advantage of a single portal is that it is easy to control.

"Reprint" The advantages and disadvantages of DELEGATE,NOTIFICATION,KVO three modes in iOS for communicationOriginal address:http://blog.csdn.net/yangxt/article/details/8176636In developing iOS, there are three modes for communicating between controllers:1. Entrust delegation;2. Notification Centre Notification Center;3. Key value Observing,kvoSo why do we need these patterns and when to use it and when not to do it.1.delegateBasic Features:A controll