HAddLink (Function)

Adds an integrity rule between two data files on the server. This integrity rule was previously described by a Link description variable. All the client applications must comply with these integrity rules.

Remark: You have the ability to describe inter-database integrity rules.

The addition will be effective for the application that performed it once the connection has been closed and re-opened.

Remark: From version 19, HFSQL is the new name of HyperFileSQL.

Versions 22 and later

This function is now available in Universal Windows 10 App mode.

New in version 22

This function is now available in Universal Windows 10 App mode.

Versions 24 and later

This function is now available for iPhone/iPad applications.

New in version 24

This function is now available for iPhone/iPad applications.

Example

// Describe the connection
HDescribeConnection("MyConnection", "Julia", "Password", "MyHFServer", ...
"MyDatabase", hAccessHFClientServer, hORead)
// Open the connection
HOpenConnection("MyConnection")
...
MyLink is Link Description
// Describe the "LIVES" link
MyLink..Name = "LIVES"
MyLink..SourceFile = ".\MyDatabase\city.fic"
MyLink..LinkedFile = ".\MyDatabase\customer.fic"
MyLink..SourceKey = "CITYNAME"
MyLink..LinkedKey = "CUSTCITY"
// Default link (0-1, 0-1)
HAddLink("MyConnection", MyLink)

Syntax

<Result> = HAddLink(<Source connection> [, <Linked connection>] , <Link>)

<Result>: Boolean

True if the operation was performed,
False if a problem occurred. HErrorInfo is used to identify the error.

<Source connection>: Character string (with or without quotes) or Connection variable

Connection to which belongs the source file of the link. This connection corresponds to:
the name of the connection defined in the data model editor or with HDescribeConnection or HOpenConnection.
a Connection variable.

<Linked connection>: Optional character string (with or without quotes) or Connection variable

Connection to which belongs the linked file of the link. This connection corresponds to:
the connection defined in the data model editor or with HDescribeConnection or HOpenConnection.
a Connection variable.
If this parameter is not specified, both data files will belong to the same connection (<Source connection>).

<Link>: Link Description variable

Name of the Link description variable containing the characteristics of the link to create.

Remarks

Link description

During the description of the link, the names of the data files involved in the link (..SourceFile and ..LinkedFile) must correspond to the physical names of the data files, relative to the relevant Database. The Database of each file is returned by <Source connection> and <Linked connection>

Various

HDescribeLink is used to describe a temporary link on an ISAM database (not in Client/Server mode) or for the client application only (not on the server).
HDeleteLink is used to delete a link on the server.

Component : wd250hf.dll