Integrating SQL Server with Visual FoxPro
Robert Green
Microsoft Corporation
January 1997

Introduction

Your good friends on the Visual FoxPro™ team at Microsoft® spent a great deal of time to make Visual FoxPro a robust and powerful front-end for client-server applications. Remote views and SQL pass-through provide powerful tools to take advantage of SQL back-ends such as Oracle and Microsoft SQL Server via ODBC (Open Database Connectivity).
One of the great truisms of application development is that there are many ways to do everything. One of the hardest things to do when building an application is to decide on an approach and to know if it is better than the other approaches. In client-server development this is compounded by …ver más…

A row is then added to the Adult or Juvenile table and the value for the member_no will be whatever is in @@Identity.

Declarative Referential Integrity

In prior versions of SQL Server referential integrity was enforced through the use of triggers, which is the same way Visual FoxPro enforces referential integrity. SQL Server 6.0 added declarative referential integrity, which allows you to define your RI rules as part of the data structure. The first step is to create a Primary Key constraint in each table, as shown in the following code:
ALTER TABLE member

ADD CONSTRAINT member_ident PRIMARY KEY CLUSTERED

(member_no)

ALTER TABLE adult

ADD CONSTRAINT adult_ident PRIMARY KEY CLUSTERED

(member_no)

ALTER TABLE juvenile

ADD CONSTRAINT juvenile_ident PRIMARY KEY CLUSTERED

(member_no)
The Primary Key constraint creates a Unique index, which enforces the uniqueness of the member_no. In the examples here a clustered index, which physically sorts the data, is created.
The second step in defining declarative referential integrity is to create Foreign Key constraints between related tables, as shown in the following code:
ALTER TABLE adult

ADD CONSTRAINT adult_member_link FOREIGN KEY (member_no)

REFERENCES member (member_no)

ALTER TABLE juvenile

ADD CONSTRAINT juvenile_member_link FOREIGN KEY

(member_no) REFERENCES member (member_no)

ALTER TABLE juvenile

ADD CONSTRAINT