HOWTO: Retrieve Foreign Key Information from SQL Server
ID: Q196084
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The information in this article applies to:
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Microsoft Visual FoxPro for Windows, versions 3.0, 3.0b, 5.0, 5.0a, 6.0
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Microsoft Visual FoxPro for Macintosh, version 3.0b
SUMMARY
When creating remote views using SQL Server tables as the data source,
Visual FoxPro automatically sets the KeyField property to .T. for columns
that are included in a primary index key. You can use the SQL Server stored
procedure, sp_pkeys, to return primary key information from SQL Server. The
sp_pkeys stored procedure, however, does not return information regarding
the relationship(s) between tables.
In some circumstances, a developer may want to retrieve the foreign key
information programmatically to provide greater detail of the relationship
between tables. This article shows how to use the stored procedure sp_fkeys
to return foreign key information from SQL Server.
MORE INFORMATION
The sp_fkeys stored procedure returns a cursor with logical foreign key
information for the current environment. This procedure shows foreign key
relationships including disabled foreign keys. The sp_fkeys stored
procedure is equivalent to SQLForeignKeys in ODBC. The results returned are
ordered by FKTABLE_QUALIFIER, FKTABLE_OWNER, FKTABLE_NAME, and KEY_SEQ.
The columns returned by sp_fkeys follow:
Column Name Description
-----------------------------------------------------------------------
PKTABLE_QUALIFIER Name of the table (with the primary key) qualifier.
This column represents the database name for the
table with a PRIMARY KEY constraint and may be
NULL.
PKTABLE_OWNER Name of the table (with the primary key) owner.
This column represents the name of the database
user that created the table (with a PRIMARY KEY
constraint) and always returns a value.
PKTABLE_NAME Name of the table (with the primary key). This
column represents the table name (with a PRIMARY
KEY constraint) as listed in the sysobjects table
and always returns a value.
PKCOLUMN_NAME Name of the primary key column(s), for each column
of the TABLE_NAME returned. This column represents
the column name as listed in the syscolumns table
and always returns a value.
FKTABLE_QUALIFIER Name of the table (with a foreign key) qualifier.
This column represents the database name for the
table (with a FOREIGN KEY constraint) and may be
NULL.
FKTABLE_OWNER Name of the table (with a foreign key) owner. This
column represents the name of the database user
that created the table (with a FOREIGN KEY
constraint) and always returns a value.
FKTABLE_NAME Name of the table (with a foreign key). This column
represents the table name as listed in the
sysobjects table (with a FOREIGN KEY constraint)
and always returns a value.
FKCOLUMN_NAME Name of the foreign key column(s), for each column
of the TABLE_NAME returned. This column represents
the column name as listed in the syscolumns table
and always returns a value.
KEY_SEQ Sequence number of the column in a multicolumn
primary key. This field always returns a value.
UPDATE_RULE Action applied to the foreign key when the SQL
operation is UPDATE. SQL Server returns 1 for this
column.
DELETE_RULE Action applied to the foreign key when the SQL
operation is DELETE. SQL Server returns 1 for this
column.
FK_NAME Foreign key identifier. This is the FOREIGN KEY
constraint name, and may be NULL if not applicable
to the data source.
PK_NAME Primary key identifier. This is the PRIMARY KEY
constraint name, and may be NULL if not applicable
to the data source.
Create a program named SP_fkeys.prg using the following code:
* Substitute the server name.
#DEFINE Connect_String 'DRIVER={SQL Server};SERVER=MY_SERVER;' + ;
'DATABASE=PUBS;UID=sa;PWD='
* Create a cursor to store information.
CREATE CURSOR SQLKeys (Parent_Qualifier c(128), Parent_Owner c(128), ;
Parent_Table_Name c(128), Parent_Column_Name c(128), ;
Foreign_Qualifier c(128), Foreign_Owner c(128), ;
Foreign_Table_Name c(128), Foreign_Column_Name c(128), ;
Key_Seq I, FK_NAME c(128), PK_Name c(128))
* Connect to SQL Server.
gnConnHandle=SQLSTRINGCONN(Connect_String)
IF gnConnHandle>0
* Get the tables available on SQL Server.
SQLConnTables=SQLTABLES(gnConnHandle)
IF SQLConnTables>0
SELECT SQLResult
INCnt=0
DO WHILE !EOF()
* Create a command to execute the stored procedure.
SQLCommand="sp_fkeys " + ALLTRIM(Table_Name)
* Execute the stored procedure and return data to a cursor.
=SQLEXEC(gnConnHandle,SQLCommand,'syskeys')
* Select the cursor.
SELECT SYSKeys
IF RECCOUNT()>0
SELECT SQLKeys
SQLKEY_Exists=.F.
SCAN FOR Parent_Table_Name=SYSKeys.PKTable_Name ;
AND Foreign_Table_Name=SYSKeys.FKTable_Name
* Multicolumn key.
* Concatenate to get the expression.
REPLACE SQLKeys.Foreign_Column_Name WITH ;
ALLTRIM(SQLKeys.Foreign_Column_Name) + ;
"+" + ALLTRIM(SYSKeys.FKColumn_Name)
SQLKEY_Exists=.T.
ENDSCAN
IF !SQLKEY_Exists
* Insert a new record into the SQLKeys cursor.
INSERT INTO SQLKeys ;
VALUES ;
(SYSKeys.PKTable_Qualifier, SYSKeys.PKTable_Owner, ;
SYSKeys.PKTable_Name, SYSKeys.PKColumn_Name, ;
SYSKeys.FKTable_Qualifier, SYSKeys.FKTable_Owner, ;
SYSKeys.FKTable_Name,SYSKeys.FKColumn_Name, ;
SYSKeys.Key_Seq,SYSKeys.FK_NAME,SYSKeys.PK_Name)
ENDIF
ENDIF
SELECT SQLResult
SKIP
ENDDO
=SQLDISCONN(gnConnHandle)
ENDIF
ENDIF
SELECT SQLKeys
BROW LAST
CLOSE ALL
RETURN
In the Command window enter and run the following code:
DO SP_FKEYS
REFERENCES
Transact - SQL Help; search on: "sp_fkeys"
(c) Microsoft Corporation 1998, All Rights Reserved. Contributions by
John Desch, Microsoft Corporation.
Additional query words:
Keywords : kbClient KbClientServer kbDatabase kbSQL kbVFp kbVFp300b kbVFp500 kbVFp500a kbVFp600
Version : MACINTOSH:3.0b; WINDOWS:3.0,3.0b,5.0,5.0a,6.0
Platform : MACINTOSH WINDOWS
Issue type : kbhowto