Realizar consultas distribuidas de SQL Server con archivos .dbf de FoxPro

2020-09-08

En este artículo se presenta cómo realizar una consulta distribuida de SQL Server para recuperar datos de archivos .dbc y .dbf de FoxPro mediante el controlador ODBC VFP o el proveedor OLE DB VFP.

Versión original del producto: Visual FoxPro
Número de KB original: 207595

Resumen

En este artículo se muestra cómo realizar una consulta distribuida de SQL Server para recuperar datos de FoxPro .dbc y .dbf archivos mediante el controlador ODBC VFP o el proveedor OLE DB VFP.

Más información

Microsoft SQL Server 2000 proporciona la capacidad de realizar consultas en proveedores OLE DB. Esta consulta se realiza mediante las OpenQuery funciones o OpenRowset Transact-SQL o mediante una consulta con nombres de cuatro partes, incluido un nombre de servidor vinculado.

Por ejemplo:

sp_addlinkedserver 'mylinkedserver', 'product_name', 'myoledbprovider', 'data_source','location', 'provider_string', 'catalog'

SELECT * FROM OPENQUERY(mylinkedserver, 'select * from table1')

Debe usar el proveedor OLE DB de Microsoft para ODBC (MSDASQL) y el controlador ODBC de Visual FoxPro para configurar un servidor vinculado para realizar consultas distribuidas en FoxPro .dbc y .dbf archivos. No se admite el uso del proveedor Jet OLEDB con FoxPro. El controlador ODBC de VFP no es seguro para los hilos. Dado que SQL Server es multiproceso, el controlador ODBC VFP puede causar problemas en algunas circunstancias. Si es posible, se recomienda usar el proveedor OLE DB de VFP para conectarse a los datos de SQL Server.

En el siguiente ejemplo de código T-SQL se muestra cómo configurar y usar consultas distribuidas con FoxPro con funciones OpenQuery y OpenRowset. También muestra cómo actualizar una tabla foxPro remota de SQL Server 2000. Puede probar este código en el Analizador de consultas SQL después de instalar el controlador ODBC de Visual FoxPro en una máquina de SQL Server 2000. Deberá cambiar los nombres de origen de datos y la ruta de acceso a los archivos FoxPro según corresponda:

/* OPENROWSET and OPENQUERY examples with VFP via ODBC OLE DB provider */ 

/* These OPENROWSET examples depend on the sample files VFP98\data\Testdata.dbc
Modify your code accordingly for differences in location or DBC name */ 

--====================================================
-- Using DBC file , read and update
--====================================================
-- OPENROWSET DSN-less example

select * from openrowset('MSDASQL',
'Driver=Microsoft Visual FoxPro Driver;
SourceDB=e:\VFP98\data\Testdata.dbc;
SourceType=DBC',
'select * from customer where country != "USA" order by country')
go

select * from openrowset('MSDASQL',
'Driver=Microsoft Visual FoxPro Driver;
SourceDB=e:\VFP98\data\Testdata.dbc;
SourceType=DBC',
'select * from customer where region="WA"')
go

Update openrowset('MSDASQL',
'Driver=Microsoft Visual FoxPro Driver;
SourceDB=e:\VFP98\data\Testdata.dbc;
SourceType=DBC',
'select * from customer where region="WA"')
set region = "Seattle" 
go

-- check to verify which rows were updated
select * from openrowset('MSDASQL',
'Driver=Microsoft Visual FoxPro Driver;
SourceDB=e:\VFP98\data\Testdata.dbc;
SourceType=DBC',
'select * from customer where region="Seattle"') 
go

-- OPENROWSET DSN example
/* Note the DSN Example might fail if SQL Server is configured to use a local account.*/ 
select * from openrowset('MSDASQL',
'DSN=Visual FoxPro Database;
SourceDB=e:\VFP98\data\Testdata.dbc;
SourceType=DBC',
'select * from customer where country != "USA" order by country'
go

/* sp_addlinkedserver examples */ 
-- sp_addlinkedserver example with DSN

/* You will need to make a DSN and point it to the Testdata database. 
Modify your code accordingly for differences in location or DBC name */ 

/* Note this Example may fail if SQL Server is configured to use a local account.*/ 
sp_addlinkedserver 'VFP Testdata Database With DSN', 
 '', 
 'MSDASQL',
 'VFP System DSN'
go

sp_addlinkedsrvlogin 'VFP Testdata Database With DSN', FALSE, NULL, NULL, NULL
go 

SELECT *
FROM OPENQUERY([VFP Testdata Database With DSN], 'select * from customer where region = "Seattle"') 
go

-- Update using OpenQuery
Update OPENQUERY([VFP Testdata Database With DSN], 'select * from customer where region="WA"') 
set region = &quot;Seattle&quot; 
go

/* SP_addlinkedserver example with DSN-less connection */ 

/* This example also depends on the sample files Testdata.dbc
Modify your code accordingly for differences in location or DBC name */ 

sp_addlinkedserver 'VFP Testdata Database With No DSN', 
 '', 
 'MSDASQL',
 NULL,
 NULL,
'Driver={Microsoft Visual FoxPro Driver};UID=;PWD=;SourceDB=e:\VFP98\data\Testdata.dbc;SourceType=DBC;Exclusive=No;BackgroundFetch=Yes;Collate=Machine;'
go

sp_addlinkedsrvlogin 'VFP Testdata Database With No DSN', FALSE, NULL, NULL, NULL
go

SELECT *
FROM OPENQUERY([VFP Testdata Database With No DSN], 'select * from customer where country != "USA" order by country')
go

--====================================================
-- Using VFP 6.0 driver, read and update data from VFP sample dbf files
--====================================================

-- OPENROWSET DSN-less example

select * from openrowset('MSDASQL',
'Driver=Microsoft Visual FoxPro Driver;
SourceDB=e:\VFP98\data;
SourceType=DBF',
'select * from customer where country != "USA" order by country')
go

-- perform UPDATE

Update openrowset('MSDASQL',
'Driver=Microsoft Visual FoxPro Driver;
SourceDB=e:\VFP98\data;
SourceType=DBF',
'select * from customer where region="Seattle"')
set region = "WA"
go

-- verify update

select * from openrowset('MSDASQL',
'Driver=Microsoft Visual FoxPro Driver;
SourceDB=e:\VFP98\data;
SourceType=DBF',
'select * from customer where region = "WA"')
go&amp;lt;BR/&amp;gt;

-- OPENROWSET DSN example
-- DSN points to the folder where .dbf files are.
/* Note this Example may fail if SQL Server is configured to use a local account.*/ 
select * from openrowset('MSDASQL',
'DSN=Visual FoxPro Tables;
SourceDB=e:\VFP98\data;
SourceType=DBF',
'select * from customer where country != "USA" order by country') 
go"?
-- SQL Server's QUOTED_IDENTIFIER has to be set to OFF.

SET QUOTED_IDENTIFIER OFF

-- OPENROWSET DSN-less example

select * from openrowset('MSDASQL',

'Driver=Microsoft Visual FoxPro Driver;

SourceDB=e:\VFP90\samples\data\Testdata.dbc;

SourceType=DBC',

'select * from customer where country = "USA" order by city')

go

select * from openrowset('MSDASQL',

'Driver=Microsoft Visual FoxPro Driver;

SourceDB=e:\VFP90\samples\data\Testdata.dbc;

SourceType=DBC',

'select * from customer where region="WA"')

go

Update openrowset('MSDASQL',

'Driver=Microsoft Visual FoxPro Driver;

SourceDB=e:\VFP90\samples\data\Testdata.dbc;

SourceType=DBC',

'select * from customer where city = "Seattle"')

set region = "WW" 

go

-- check to verify which rows were updated

select * from openrowset('MSDASQL',

'Driver=Microsoft Visual FoxPro Driver;

SourceDB=e:\VFP90\samples\data\Testdata.dbc;

SourceType=DBC',

'select * from customer where region="WW"') 

go

-- OPENROWSET DSN example

/* Note the DSN Example might fail if SQL Server is configured to use a local account.*/ 

select * from openrowset('MSDASQL',

'DSN=Visual FoxPro Database;

SourceDB=e:\VFP90\samples\data\Testdata.dbc;

SourceType=DBC',

'select * from customer where country = "USA" order by city')

go

/* sp_addlinkedserver examples */ 

-- sp_addlinkedserver example with DSN

/* You will need to make a DSN and point it to the Testdata database. 

Modify your code accordingly for differences in location or DBC name */ 

/* Note this Example may fail if SQL Server is configured to use a local account.*/ 

sp_addlinkedserver 'VFP Testdata Database With DSN', 

'', 

'MSDASQL',

'VFP System DSN'

go

sp_addlinkedsrvlogin 'VFP Testdata Database With DSN', FALSE, NULL, NULL, NULL

go 

SELECT *

FROM OPENQUERY([VFP Testdata Database With DSN], 'select * from customer where city = "Seattle" ') 

go

-- We will set the region back to "WA" if it currently is "WW".

-- Update using OpenQuery

Update OPENQUERY([VFP Testdata Database With DSN], 'select * from customer where city = "Seattle" ') 

set region = "WA" 

go

-- Make sure that the region got updated.

SELECT *

FROM OPENQUERY([VFP Testdata Database With DSN], 'select * from customer where city = "Seattle" ') 

go

/* SP_addlinkedserver example with DSN-less connection */ 

/* This example also depends on the sample files Testdata.dbc

Modify your code accordingly for differences in location or DBC name */ 

sp_addlinkedserver 'VFP Testdata Database With No DSN', 

'', 

'MSDASQL',

NULL,

NULL,

'Driver={Microsoft Visual FoxPro Driver};UID=;PWD=;SourceDB=e:\VFP90\samples\data\Testdata.dbc;SourceType=DBC;Exclusive=No;BackgroundFetch=Yes;Collate=Machine;'

go

sp_addlinkedsrvlogin 'VFP Testdata Database With No DSN', FALSE, NULL, NULL, NULL

go

SELECT *

FROM OPENQUERY([VFP Testdata Database With No DSN], 'select * from customer where country = "USA" order by city') 

go

--====================================================

-- Using VFP 6.0 driver, read and update data from VFP sample dbf files

--====================================================

-- OPENROWSET DSN-less example

select * from openrowset('MSDASQL',

'Driver=Microsoft Visual FoxPro Driver;

SourceDB=e:\VFP90\samples\data;

SourceType=DBF',

'select * from customer where country != "USA" order by country')

go

-- perform UPDATE

Update openrowset('MSDASQL',

'Driver=Microsoft Visual FoxPro Driver;

SourceDB=e:\VFP90\samples\data;

SourceType=DBF',

'select * from customer where city = "Seattle"')

set region = "WW" 

go

-- verify update

select * from openrowset('MSDASQL',

'Driver=Microsoft Visual FoxPro Driver;

SourceDB=e:\VFP90\samples\data;

SourceType=DBF',

'select * from customer where region = "WW"')

go

-- OPENROWSET DSN example

-- DSN points to the folder where .dbf files are.

/* Note this Example may fail if SQL Server is configured to use a local account.*/ 

select * from openrowset('MSDASQL',

'DSN=Visual FoxPro Tables; 

SourceDB=e:\VFP90\samples\data;

SourceType=DBF',

'select * from customer where country != "USA" order by country') 

go

También puede usar el proveedor OLE DB de Visual FoxPro para crear una consulta distribuida. Es la tecnología preferida para usar. Aunque este código muestra cómo actualizar y eliminar datos, no se admite la adición, actualización (edición) y eliminación de datos en una consulta distribuida mediante el proveedor OLE DB.

En el siguiente ejemplo de código T-SQL se muestra cómo configurar y usar consultas distribuidas con FoxPro con OpenQuery y OpenRowset funciones. Puede probar este código en el Analizador de consultas SQL después de instalar el proveedor OLE DB de Visual FoxPro en una máquina de SQL Server 2000. Deberá cambiar los nombres de origen de datos y la ruta de acceso a los archivos FoxPro según corresponda:

 '/* These OPENROWSET examples depend on the sample files VFP98\data\Testdata.dbc

'Modify your code accordingly for differences in location or DBC name */

--*====================================================

--* Using the DBC file, reading and updating data.

--*====================================================

--* A couple of OPENROWSET queries.

select * from openrowset('VFPOLEDB',

'e:\vfp7junk\Testdata.dbc';'Exclusive=No';'Data Source=DBC',

'select * from customer where country != "USA" order by country')

go

Select * from openrowset('VFPOLEDB',

'e:\vfp7junk\Testdata.dbc';'Exclusive=No';'Data Source=DBC',

'select * from customer where region="WA"')

go

--* Need to use an error trapping routine with the UPDATE and DELETE functions:

select * from

openrowset('VFPOLEDB',

'E:\VFP7Junk\Testdata.DBC';'Exclusive=No';'Data Source=DBC',

'Update Customer Set city = "SEATTLE" where region = "WA" ') 

go

declare @upderror int

select @upderror = @@error

print ''

if @upderror != 7357 and @upderror != 0

print 'Update failed with error '+convert(varchar(5),@upderror)

else

print 'Ignore the error above, the Update succeeded'

go

-- check to verify which rows were updated

select * from openrowset('VFPOLEDB',

'E:\VFP7junk\Testdata.DBC';'Exclusive=No';'Data Source=DBC',

'select * from customer where region = "WA"')

go

--* Change the City field back to "Seattle".

select * from

openrowset('VFPOLEDB',

'E:\VFP7Junk\Testdata.DBC';'Exclusive=No';'Data Source=DBC',

'Update Customer Set city = "Seattle" where region = "WA" ') 

go

declare @upderror int

select @upderror = @@error

print ''

if @upderror != 7357 and @upderror != 0

print 'Update failed with error '+convert(varchar(5),@upderror)

else

print 'Ignore the error above, the Update succeeded'

go

--* The DELETE fucntion also causes an error, but the DELETE works.

select * from

openrowset('VFPOLEDB',

'E:\VFP7Junk\Testdata.DBC';'Exclusive=No';'Data Source=DBC',

'Delete from Customer where country = "Spain" ') 

go

declare @delerror int

select @delerror = @@error

print ''

if @delerror != 7357 and @delerror != 0

print 'Delete failed with error '+convert(varchar(5),@delerror)

else

print 'Ignore the error above, the Delete succeeded'

go

--* Check to see that the records are deleted.

Select * from openrowset('VFPOLEDB',

'e:\vfp7junk\Testdata.dbc';'Exclusive=No';'Data Source=DBC',

'select * from customer where country = "Spain"')

go

--* Here are some examples using the VFP OLE DB Provider to create Linked Servers.

--* Using sp_addlinkedserver to create the Linked Server.

sp_addlinkedserver @server='VFP_Linked_Server',

@srvproduct='Microsoft Visual FoxPro OLE DB Provider', 

@provider='VFPOLEDB',

@datasrc = 'E:\vfp7junk'

go

SELECT *

FROM OPENQUERY([VFP_Linked_Server], 'select * from customer where city = "Seattle"')

go

-- The Update command will update the table with the OPENQUERY function when using the 

-- linked server, but the same error 7357 error will occur.

select * from

OPENQUERY([VFP_Linked_Server],

'Update Customer Set city = "SEATTLE" where region = "WA" ') 

go

declare @upderror int

select @upderror = @@error

print ''

if @upderror != 7357 and @upderror != 0

print 'Update failed with error '+convert(varchar(5),@upderror)

else

print 'Ignore the error above, the Update succeeded'

go

-- Check and see if the City field is all uppercase with "SEATTLE".

SELECT *

FROM OPENQUERY([VFP_Linked_Server], 'select * from customer where region = "WA"')

go

--* Let's check for how many records have the word "London" in the City field.

SELECT *

FROM OPENQUERY([VFP_Linked_Server], 'select * from customer where city = "London"')

go

-- We can also use the Delete command to remove records with the OPENQUERY function when using the 

-- linked server, but the same error 7357 error will occur.

select * from

OPENQUERY([VFP_Linked_Server],

'Delete from Customer where city = "London"') 

go

declare @delerror int

select @delerror = @@error

print ''

if @delerror != 7357 and @delerror != 0

print 'Delete failed with error '+convert(varchar(5),@delerror)

else

print 'Ignore the error above, the Delete succeeded'

go

/* SP_addlinkedserver example with DSN-less connection */

/* This example also depends on the sample files Testdata.dbc

Modify your code accordingly for differences in location or DBC name */

sp_addlinkedserver 'VFP Testdata Database With No DSN',

'',

'MSDASQL',

NULL,

NULL,

'Driver={Microsoft Visual FoxPro Driver};UID=;PWD=;SourceDB=e:\VFP8junk\Testdata.dbc;SourceType=DBC;Exclusive=No;BackgroundFetch=Yes;Collate=Machine;'

go

SELECT *

FROM OPENQUERY([VFP Testdata Database With No DSN], 'select * from customer where country = "USA" order by country')

go

Referencias

Para obtener más información sobre cómo configurar y usar consultas distribuidas, eche un vistazo a sp_addlinkedserver, OpenQuery, OpenRowset y temas relacionados en los Libros en línea de SQL 7.0.

Para obtener más información sobre FoxPro y .dbf.dbc archivos, consulte la documentación del producto FoxPro.

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Realizar consultas distribuidas de SQL Server con archivos .dbf de FoxPro

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