18th Chapter-delphi Client Server application Development (III.) (1)

3. Installed software projects

When you install the InterBase SQL link driver, the following items will be installed on your workstation.

Table 18.7 installed file names

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Project description

──────────────────────────────────────

Sqld-ib. DLL contains dynamic link libraries for interbase drivers and supporting files

SQLINT32. Dll

The Intrbase drive type is added to the driver management program of the Configuration tool to configure the basic Borland

InterBase SQL Link Driver

Intrbase alias type is added to the alias of the configuration file to create a connection to the SQL Server database.

Alias

Sqld_ib. HLP configuration InterBase driver's Help file

Readlink. TXT Borland SQL Links for Windows Readme file

Interbas. MSG interbase message file, usually installed on C:\INTERBAS

CONNECT. EXE test Workstation and InterBase server connectivity Tools

REMOTE. DLL, interbase support dynamic link library

Gds. DLL, GDS32. Dll

The InterBase server description installation process modifies the workstation's services file to increase

Join the Services file interbase the protocol description required for server access,

such as: Gds-db 3050/tcp

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The software project should also include TCP/IP interface software

The files listed in the following table provide an interface for InterBase client applications to access Winsock 1.1

Table 18.8 TCP/IP interface software

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FileName description

────────────────────────────────

Mvwasync. EXE Asynchronous Communication Module

Vsl.int tcp/1p Transport Initialization file

WINSOCK. DLL Windows socket Dynamic link library

Msocklib. DLL maps Windows socket calls to the VSL driver

━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

If the TCP/IP product is not Winsock1.1 compatible, the InterBase client application will also be able to take other tcp/1p drivers. InterBase servers can also support other communication protocols, such as SPX/1PX,NETBEIU.

4. Addressing general connectivity issues

If you have problems establishing a connection to a interbase server with SQL links, you can isolate the problem by using the following steps:

⑴ the Windows isql tool to test the ability to join the InterBase server

If successful, the status information appears and the step ⑵ continues.

If it is unsuccessful, ask the database administrator.

⑵ Verify that the InterBase SQL Links driver is properly installed.

⑶ to reinstall SQL Links.

⑷ Check Services, there should be lines in the file:

gds_db 3050/tcp

If it is not installed correctly, ask the database administrator or continue with step ⑸.

⑸ Test underlying protocol

① Enter the telnet command to confirm that the TCP library is properly installed.

If the TCP library is installed correctly, the registration prompt appears. Registration network Check whether the database exists.

If the message is "can ' t resolve hostname" appears, check the workstation's Hosts file for your host name and IP address of the population. Such as:

128.127.50.12 Mis_server

If you are successful with Telnet, but still cannot join correctly, the InterBase is not installed correctly. Please find

Ask the database administrator for help.

②ping to the server server, test that the InterBase server is running correctly and visible for desktop applications

(If the ping is successful, the message "ServerName is Alive" is displayed).

Ping succeeds but Telnet is unsuccessful, there may be a problem with the inet daemon.

If the ping is unsuccessful on the server, there is a network path problem and the problem is reported to the network administrator.

If the underlying protocol is not normal, ask the database administrator or continue to help ⑹.

⑹ confirm that you have access to the InterBase server, if you want to continue with step ⑺.

⑺ Check that the InterBase alias for the BDE application is properly installed.

If you can join directly from a workstation, but not from a BDE application, it is possible that your

IDAPI32. There is a problem with the CFG alias settings. Run the BDE Configuration tool to check the InterBase alias.

18.3 Delphi Client/server Programming

This section describes how to develop a Client\server database application using the Delphi Visual development tool and the objectpascal language, using the example Csdemos. This is an example of Delphi2.0 's demo Client\server development, which is installed in C:\Program files\borland\delphi 2.0\demos\db\csdemos (default installation).

This section will contain the following:

Using the Tdatabase part to connect to a SQL Server

Joins the Tdatabase part and accesses the database and how the various tables switch between the dataset part (also known as the dataset part), such as Ttable and Tquery

Using Database connections

How triggers are used

How to use Tstoredproc parts

Transaction control between the client and the server

How to use Tstoredproc parts