Access入门教程 18.1 何时使用导入或联接
在Access中，可以很方便地从外部数据库中获取数据，这些数据库包括现在所有的各种主流数据库，像Dbase、 Sybase、Oracle、Foxpro等。这样你就不用去一个一个地重新输入原来的数据了。在Access中，可以用获取外部数据命令来获取外部数据库的数据，这个命令包
在Access中，可以很方便地从外部数据库中获取数据，这些数据库包括现在所有的各种主流数据库，像Dbase、 Sybase、Oracle、Foxpro等。这样你就不用去一个一个地重新输入原来的数据了。在Access中，可以用"获取外部数据"命令来获取外部数据库的数据，这个命令包括两种方式"导入"和"链接表".对于不同的外部数据库可以用不同的获取方式。而且在Access中，不光可以获取外部数据，还可以导出别的数据库，就是将用Access建立的数据库保存为别的数据库形式，像 FOXPRO,DBASE数据库等。
单击"文件"菜单中的"获取外部数据"项，弹出一个子菜单，上面有"导入"和"链接表"两个选项。我们单击其中的一个选项就可以实现导入或联接一个外部的数据库。虽然这两个命令的功用都是打开外部的一个数据库，并从中获取需要的数据，但在使用上，还是有差别的。
在我们使用"导入"这个方法来获取外部数据时需要注意几个条件。
一、需要我们打开的数据库文件相对来说比较小，而且不会被其他数据库应用程序的用 户频繁更改。
二、不需要与其他数据库应用程序的用户共享数据。
三、你正在替换以前的数据库应用程序，而且不再需要以前的数据格式。
四、在使用其他数据库中的数据时，需要最佳性能。
使用"链接表"方法来获取外部数据时也需要注意几个条件：
一、需要打开的文件比较大，甚至比本地Access数据库的最大容量（1GB）还要大。
二、这个文件经常被其他数据库应用程序的用户更改。
三、必须在网络上与其他数据库应用程序的用户共享这个文件。
四、需要把应用程序分布到几个单独的用户那里，而且，你可能要不断更新开发的应用程序接口，将"应用程序"与数据分开可以更容易地更新应用程序，而不会干扰用户积累的数据。
这就是为什么要在"获取外部数据"这个过程当中设置两种方法。如果要用的数据库并不大，但每天都可能要修改，而且由几个人来修改不同的部分，对于这种情况，最重要的是每天都有新的数据要处理，而单纯的将表导入进来，由于在Access中开发新的系统需要一定的时间，在这段时间内就有可能有新的数据输入进来。开始导入的数据就有很多可能已经更新了。所以这时使用"链接表"就不会出现这种问题，干扰到别的用户积累的数据。当然在Access中执行现在这台机器上的数据库文件是最快的，使用链接常常会因为很多原因使你的工作变得很慢，这点是你必须考虑的。
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
How to use sql if statement
Apr 09, 2025 pm 06:12 PM
SQL IF statements are used to conditionally execute SQL statements, with the syntax as: IF (condition) THEN {statement} ELSE {statement} END IF;. The condition can be any valid SQL expression, and if the condition is true, execute the THEN clause; if the condition is false, execute the ELSE clause. IF statements can be nested, allowing for more complex conditional checks.
How to configure zend for apache
Apr 13, 2025 pm 12:57 PM
How to configure Zend in Apache? The steps to configure Zend Framework in an Apache Web Server are as follows: Install Zend Framework and extract it into the Web Server directory. Create a .htaccess file. Create the Zend application directory and add the index.php file. Configure the Zend application (application.ini). Restart the Apache Web server.
How to solve the 'Network Error' caused by Vue Axios across domains
Apr 07, 2025 pm 10:27 PM
Methods to solve the cross-domain problem of Vue Axios include: Configuring the CORS header on the server side using the Axios proxy using JSONP using WebSocket using the CORS plug-in
Unable to log in to mysql as root
Apr 08, 2025 pm 04:54 PM
The main reasons why you cannot log in to MySQL as root are permission problems, configuration file errors, password inconsistent, socket file problems, or firewall interception. The solution includes: check whether the bind-address parameter in the configuration file is configured correctly. Check whether the root user permissions have been modified or deleted and reset. Verify that the password is accurate, including case and special characters. Check socket file permission settings and paths. Check that the firewall blocks connections to the MySQL server.
What are the benefits of multithreading in c#?
Apr 03, 2025 pm 02:51 PM
The advantage of multithreading is that it can improve performance and resource utilization, especially for processing large amounts of data or performing time-consuming operations. It allows multiple tasks to be performed simultaneously, improving efficiency. However, too many threads can lead to performance degradation, so you need to carefully select the number of threads based on the number of CPU cores and task characteristics. In addition, multi-threaded programming involves challenges such as deadlock and race conditions, which need to be solved using synchronization mechanisms, and requires solid knowledge of concurrent programming, weighing the pros and cons and using them with caution.
Summary of phpmyadmin vulnerabilities
Apr 10, 2025 pm 10:24 PM
The key to PHPMyAdmin security defense strategy is: 1. Use the latest version of PHPMyAdmin and regularly update PHP and MySQL; 2. Strictly control access rights, use .htaccess or web server access control; 3. Enable strong password and two-factor authentication; 4. Back up the database regularly; 5. Carefully check the configuration files to avoid exposing sensitive information; 6. Use Web Application Firewall (WAF); 7. Carry out security audits. These measures can effectively reduce the security risks caused by PHPMyAdmin due to improper configuration, over-old version or environmental security risks, and ensure the security of the database.
How to monitor Nginx SSL performance on Debian
Apr 12, 2025 pm 10:18 PM
This article describes how to effectively monitor the SSL performance of Nginx servers on Debian systems. We will use NginxExporter to export Nginx status data to Prometheus and then visually display it through Grafana. Step 1: Configuring Nginx First, we need to enable the stub_status module in the Nginx configuration file to obtain the status information of Nginx. Add the following snippet in your Nginx configuration file (usually located in /etc/nginx/nginx.conf or its include file): location/nginx_status{stub_status
What is apache server? What is apache server for?
Apr 13, 2025 am 11:57 AM
Apache server is a powerful web server software that acts as a bridge between browsers and website servers. 1. It handles HTTP requests and returns web page content based on requests; 2. Modular design allows extended functions, such as support for SSL encryption and dynamic web pages; 3. Configuration files (such as virtual host configurations) need to be carefully set to avoid security vulnerabilities, and optimize performance parameters, such as thread count and timeout time, in order to build high-performance and secure web applications.
