how to use fidelity

What is a foreign key A foreign key (FK) is one or more columns that are used to establish and strengthen a link between two table data. You can create a link between two tables by adding one or more columns that hold the primary key values in the table to another table. This column becomes the foreign key of the second table. Why foreign keys are used. Ensure referential integrity of data It's not going to happen. No, not much. If a robust system, the data in the database must have goo

Use PHP to develop robust Code 2 to effectively use variables. "Developing robust code with PHP" is a series of articles on solving practical problems in large and medium-sized applications. In this article, PHP veteran AmolHatwar discusses how to effectively use variables. "Developing robust code with PHP" is a series of articles on solving practical problems in

Google Earth to Google Earth how to use it? Google Planet from the release to now there are some years, but about how Google Earth to use the relevant profile is not much. Today, with you briefly say how Google Earth use, how to use Google Earth to query our location. Google Earth A, Google Earth profile

Use Cases can capture the funtion requirements of your systems and definate the border of the system. One use case can simulate one of the using ways of your system, that is, the event that triggered by users from outer system what sequence actions will be adpted. Each use case is a complete system usage method. Includes the description of internal events caused

when do I use references? And when to use pointers1. The question was raised:What is the difference between using value passing and reference passing when an object of a class is passed as a real argument?For example: Datetype examplefun (CString strfilename,...) AndDatetype Examplefun (CString strfilename,...)Before we answer, let's take a look at 2 basic concepts: formal parameters and arguments.The commo

About version control: A long time ago, people suffered from version management for the code they had written. After a while, they often tried to restore the code they had previously written, but they forgot where they lost it, some people use the method of naming files with time suffixes to facilitate later maintenance. However, this process is very troublesome and takes a long time, I will also forget when to save the file for

Zen Road Download Address: Http://www.zentao.net/download, there are open-source version and pay version of the choice. Project View: project manager Create build, select Product, enter name number, to test the version number of each change package; Product View: 1, the project Manager to publish, enter the name of the release, select Build version, Release date, after all the tests are completed to publish, build version selected can be published version; Test View:

Simple use of Jackson, simple use of Jackson1 Overview Jackson has high serialization and deserialization efficiency. According to tests, no matter which form of conversion, Jackson> Gson> Json-lib, in addition, Jackson's processing capability is about 10 times higher than that of Json-lib, And the correctness is also very high. In contrast, Json-lib seems to have stopped updating. The latest version is bas

Example of PHP anonymous function and use clause usage, and example of anonymous use clause. Example of PHP anonymous function and use clause usage. example of anonymous use clause this article describes the usage of PHP anonymous function and use clause. For your reference,

Practical Use of Axure to design the App and use WebStorm (5)-implement the page function, axurewebstormSeries of articles Practical Use of Axure to design apps and use WebStorm for development (1)-use Axure to describe requirements Practical

as follows: 1) VI mytask.sh Enter the following command Date>>/home/mydate3 Cp/home/mydate3/root 2) Grant mytask.sh Execute permission chmod 744 MYTASK.S H 3) Crontab-e 4) Re-enter the command: * * * * * */root/mytask.sh. (3) How to terminate a task crontab-r means to terminate a task schedule. After the command is executed, the tasks in the crontab-e are removed. CRONTAB-L indicates which task schedules are currently in the list.2, the Linux process concept and management, process: the so-cal

Use of generic sets, use of generic Sets The restructuring of the data room charging system is nothing more than adding, deleting, modifying, and querying four database operations. In addition, we use a three-tier architecture for reconstruction, and layer D is used to deal with databases. To perform these four operations, we need to return values. addition, dele

When does MySQL use indexes or do not use indexes? Index: You can use indexes to quickly access specific information in database tables. An index is a structure that sorts the values of one or more columns in a database table, for example, the name column of the employee table. If you want to search for a specific employee by name, the index will help you get the

Debian basic use advanced, Debian use advanced After the system is installed, we can't wait to soar in the Linux system. If you are new to Linux, you may not be able to adapt to the Linux system environment for a while. The best practice for using Debian for server selection is to use non-interface terminal mode. Continuous practice is one of the most important w

Use Ruby to process text tutorials, and use ruby to process text tutorials Similar to Perl and Python, Ruby has excellent functions and is a powerful text processing language. This article briefly introduces Ruby's text data processing function and how to use Ruby to effectively process text data in different formats, whether CSV data or XML data.Ruby stringCommo

Hello, C ++ (23) 4.4.2 salary program growth Note: Use arrays to process batch data, and use a loop structure to execute repeated actions, an array of 4.4.24.4 from statement to program After learning about various expressions and statements, you can understand the words and sentences used to write the compositions. However, only words and sentences cannot constitute a meaningful article. To complete an art

How to use a one-time password to securely log on to Linux through SSH, and use a password to log on to linux through ssh Some people say that security is not a product, but a process. Although the SSH protocol is designed to use encryption technology to ensure security, if improperly used, others can still damage your system, such as weak passwords, key leaks, a

Basic use cases of redis in PHP and redisPHP. The basic use cases of redis in PHP, and the use cases of redisPHP download www. oschina. after netpredis is decompressed, it contains the lib source file, examples example, and test the basic use case of copying the lib directory to redis in PHP. redisPHP

The implementation of short code in WordPress development and the use of related functions, WordPress use Tips In fact, the implementation of short code is very simple, we only need to use the WordPress inside a function can be done short code, plus a small function of their own, you can make the short code implementation of the easy and enjoyable. Short Code Im

The most common method to satisfy the group by clause is to scan the entire table and create a new temporary table. All rows in each group in the table should be continuous, then use the temporary table to locate the group and apply the accumulate function (if any ). In some cases, MySQL can do better by accessing indexes instead of creating temporary tables. The most important prerequisite for using an index for group by is that all group by colum