OPENROWSET (Transact-SQL)

Includes all connection information that is required to access remote data from an OLE DB data source. This method is an alternative to accessing tables in a linked server and is a one-time, ad hoc method of connecting and accessing remote data by using OLE DB. For more frequent references to OLE DB data sources, use linked servers instead. For more information, see Linked Servers (Database Engine). The OPENROWSET function can be referenced in the FROM clause of a query as if it were a table name. The OPENROWSET function can also be referenced as the target table of an INSERT, UPDATE, or DELETE statement, subject to the capabilities of the OLE DB provider. Although the query might return multiple result sets, OPENROWSET returns only the first one.

OPENROWSET also supports bulk operations through a built-in BULK provider that enables data from a file to be read and returned as a rowset.

Transact-SQL Syntax Conventions

Składnia

OPENROWSET 
( { 'provider_name' , { 'datasource' ; 'user_id' ; 'password' 
   | 'provider_string' } 
   , {   [ catalog. ] [ schema. ] object 
       | 'query' 
     } 
   | BULK 'data_file' , 
       { FORMATFILE = 'format_file_path' [ <bulk_options> ]
       | SINGLE_BLOB | SINGLE_CLOB | SINGLE_NCLOB }
} ) 

<bulk_options> ::=
   [ , CODEPAGE = { 'ACP' | 'OEM' | 'RAW' | 'code_page' } ] 
   [ , ERRORFILE = 'file_name' ]
   [ , FIRSTROW = first_row ] 
   [ , LASTROW = last_row ] 
   [ , MAXERRORS = maximum_errors ] 
   [ , ROWS_PER_BATCH = rows_per_batch ]
   [ , ORDER ( { column [ ASC | DESC ] } [ ,...n ] ) [ UNIQUE ]

Arguments

• 'provider_name'
  Is a character string that represents the friendly name (or PROGID) of the OLE DB provider as specified in the registry. provider_name has no default value.

• 'datasource'
  Is a string constant that corresponds to a particular OLE DB data source. datasource is the DBPROP_INIT_DATASOURCE property to be passed to the IDBProperties interface of the provider to initialize the provider. Typically, this string includes the name of the database file, the name of a database server, or a name that the provider understands to locate the database or databases.

• 'user_id'
  Is a string constant that is the user name passed to the specified OLE DB provider. user_id specifies the security context for the connection and is passed in as the DBPROP_AUTH_USERID property to initialize the provider. user_id cannot be a Microsoft Windows login name.

• 'password'
  Is a string constant that is the user password to be passed to the OLE DB provider. password is passed in as the DBPROP_AUTH_PASSWORD property when initializing the provider. password cannot be a Microsoft Windows password.

• 'provider_string'
  Is a provider-specific connection string that is passed in as the DBPROP_INIT_PROVIDERSTRING property to initialize the OLE DB provider. provider_string typically encapsulates all the connection information required to initialize the provider. For a list of keywords that are recognized by the SQL Server Native Client OLE DB provider, see Initialization and Authorization Properties.

• catalog
  Is the name of the catalog or database in which the specified object resides.

• schema
  Is the name of the schema or object owner for the specified object.

• object
  Is the object name that uniquely identifies the object to work with.

• 'query'
  Is a string constant sent to and executed by the provider. The local instance of SQL Server does not process this query, but processes query results returned by the provider, a pass-through query. Pass-through queries are useful when used on providers that do not make available their tabular data through table names, but only through a command language. Pass-through queries are supported on the remote server, as long as the query provider supports the OLE DB Command object and its mandatory interfaces. For more information, see SQL Server Native Client (OLE DB) Reference.

• BULK
  Uses the BULK rowset provider for OPENROWSET to read data from a file. In SQL Server, OPENROWSET can read from a data file without loading the data into a target table. This lets you use OPENROWSET with a simple SELECT statement.

  The arguments of the BULK option allow for significant control over where to start and end reading data, how to deal with errors, and how data is interpreted. For example, you can specify that the data file be read as a single-row, single-column rowset of type varbinary, varchar, or nvarchar. The default behavior is described in the argument descriptions that follow.

  For information about how to use the BULK option, see "Remarks," later in this topic. For information about the permissions that are required by the BULK option, see "Permissions," later in this topic.

  [!UWAGA]

  When used to import data with the full recovery model, OPENROWSET (BULK ...) does not optimize logging.

  For information on preparing data for bulk import, see Prepare Data for Bulk Export or Import (SQL Server).

• 'data_file'
  Is the full path of the data file whose data is to be copied into the target table.

• FORMATFILE ='format_file_path'
  Specifies the full path of a format file. SQL Server supports two types of format files: XML and non-XML.

  A format file is required to define column types in the result set. The only exception is when SINGLE_CLOB, SINGLE_BLOB, or SINGLE_NCLOB is specified; in which case, the format file is not required.

  For information about format files, see Use a Format File to Bulk Import Data (SQL Server).

• < bulk_options >
  Specifies one or more arguments for the BULK option.

• CODEPAGE = { 'ACP'| 'OEM'| 'RAW'| 'code_page' }
  Specifies the code page of the data in the data file. CODEPAGE is relevant only if the data contains char, varchar, or text columns with character values more than 127 or less than 32.

  [!UWAGA]

  We recommend that you specify a collation name for each column in a format file.

  CODEPAGE value	Description
  ACP	Converts columns of char, varchar, or text data type from the ANSI/Microsoft Windows code page (ISO 1252) to the SQL Server code page.
  OEM (default)	Converts columns of char, varchar, or text data type from the system OEM code page to the SQL Server code page.
  RAW	No conversion occurs from one code page to another. This is the fastest option.
  code_page	Indicates the source code page on which the character data in the data file is encoded; for example, 850. Ważne: SQL Server does not support code page 65001 (UTF-8 encoding).

• ERRORFILE ='file_name'
  Specifies the file used to collect rows that have formatting errors and cannot be converted to an OLE DB rowset. These rows are copied into this error file from the data file "as is."

  The error file is created at the start of the command execution. An error will be raised if the file already exists. Additionally, a control file that has the extension .ERROR.txt is created. This file references each row in the error file and provides error diagnostics. After the errors have been corrected, the data can be loaded.

• FIRSTROW =first_row
  Specifies the number of the first row to load. The default is 1. This indicates the first row in the specified data file. The row numbers are determined by counting the row terminators. FIRSTROW is 1-based.

• LASTROW =last_row
  Specifies the number of the last row to load. The default is 0. This indicates the last row in the specified data file.

• MAXERRORS =maximum_errors
  Specifies the maximum number of syntax errors or nonconforming rows, as defined in the format file, that can occur before OPENROWSET throws an exception. Until MAXERRORS is reached, OPENROWSET ignores each bad row, not loading it, and counts the bad row as one error.

  The default for maximum_errors is 10.

  [!UWAGA]

  MAX_ERRORS does not apply to CHECK constraints, or to converting money and bigint data types.

• ROWS_PER_BATCH =rows_per_batch
  Specifies the approximate number of rows of data in the data file. This value should be of the same order as the actual number of rows.

  OPENROWSET always imports a data file as a single batch. However, if you specify rows_per_batch with a value > 0, the query processor uses the value of rows_per_batch as a hint for allocating resources in the query plan.

  By default, ROWS_PER_BATCH is unknown. Specifying ROWS_PER_BATCH = 0 is the same as omitting ROWS_PER_BATCH.

• ORDER ( { column [ ASC | DESC ] } [ ,... n ] [ UNIQUE ] )
  An optional hint that specifies how the data in the data file is sorted. By default, the bulk operation assumes the data file is unordered. Performance might improve if the order specified can be exploited by the query optimizer to generate a more efficient query plan. Examples for when specifying a sort can be beneficial include the following:

  • Inserting rows into a table that has a clustered index, where the rowset data is sorted on the clustered index key.

  • Joining the rowset with another table, where the sort and join columns match.

  • Aggregating the rowset data by the sort columns.

  • Using the rowset as a source table in the FROM clause of a query, where the sort and join columns match.

  UNIQUE specifies that the data file does not have duplicate entries.

  If the actual rows in the data file are not sorted according to the order that is specified, or if the UNIQUE hint is specified and duplicates keys are present, an error is returned.

  Column aliases are required when ORDER is used. The column alias list must reference the derived table that is being accessed by the BULK clause. The column names that are specified in the ORDER clause refer to this column alias list. Large value types (varchar(max), nvarchar(max), varbinary(max), and xml) and large object (LOB) types (text, ntext, and image) columns cannot be specified.

• SINGLE_BLOB
  Returns the contents of data_file as a single-row, single-column rowset of type varbinary(max).

  Ważne:
  We recommend that you import XML data only using the SINGLE_BLOB option, rather than SINGLE_CLOB and SINGLE_NCLOB, because only SINGLE_BLOB supports all Windows encoding conversions.

• SINGLE_CLOB
  By reading data_file as ASCII, returns the contents as a single-row, single-column rowset of type varchar(max), using the collation of the current database.

• SINGLE_NCLOB
  By reading data_file as UNICODE, returns the contents as a single-row, single-column rowset of type nvarchar(max), using the collation of the current database.

Uwagi

OPENROWSET can be used to access remote data from OLE DB data sources only when the DisallowAdhocAccess registry option is explicitly set to 0 for the specified provider, and the Ad Hoc Distributed Queries advanced configuration option is enabled. When these options are not set, the default behavior does not allow for ad hoc access.

When accessing remote OLE DB data sources, the login identity of trusted connections is not automatically delegated from the server on which the client is connected to the server that is being queried. Authentication delegation must be configured.

Catalog and schema names are required if the OLE DB provider supports multiple catalogs and schemas in the specified data source. Values for catalog and schema can be omitted when the OLE DB provider does not support them. If the provider supports only schema names, a two-part name of the form schema**.object must be specified. If the provider supports only catalog names, a three-part name of the form catalog.schema.**object must be specified. Three-part names must be specified for pass-through queries that use the SQL Server Native Client OLE DB provider. For more information, see Transact-SQL Syntax Conventions (Transact-SQL).

OPENROWSET does not accept variables for its arguments.

Any call to OPENDATASOURCE, OPENQUERY, or OPENROWSET in the FROM clause is evaluated separately and independently from any call to these functions used as the target of the update, even if identical arguments are supplied to the two calls. In particular, filter or join conditions applied on the result of one of those calls have no effect on the results of the other.

Using OPENROWSET with the BULK Option

The following Transact-SQL enhancements support the OPENROWSET(BULK...) function:

• A FROM clause that is used with SELECT can call OPENROWSET(BULK...) instead of a table name, with full SELECT functionality.

  OPENROWSET with the BULK option requires a correlation name, also known as a range variable or alias, in the FROM clause. Column aliases can be specified. If a column alias list is not specified, the format file must have column names. Specifying column aliases overrides the column names in the format file, such as:

  FROM OPENROWSET(BULK...) AS table_alias

  FROM OPENROWSET(BULK...) AS table_alias(column_alias,...n)

• A SELECT...FROM OPENROWSET(BULK...) statement queries the data in a file directly, without importing the data into a table. SELECT…FROM OPENROWSET(BULK...) statements can also list bulk-column aliases by using a format file to specify column names, and also data types.

• Using OPENROWSET(BULK...) as a source table in an INSERT or MERGE statement bulk imports data from a data file into a SQL Server table. For more information, see Import Bulk Data by Using BULK INSERT or OPENROWSET(BULK...) (SQL Server) .

• When the OPENROWSET BULK option is used with an INSERT statement, the BULK clause supports table hints. In addition to the regular table hints, such as TABLOCK, the BULK clause can accept the following specialized table hints: IGNORE_CONSTRAINTS (ignores only the CHECK and FOREIGN KEY constraints), IGNORE_TRIGGERS, KEEPDEFAULTS, and KEEPIDENTITY. For more information, see Table Hints (Transact-SQL).

For information about how to use INSERT...SELECT * FROM OPENROWSET(BULK...) statements, see Bulk Import and Export of Data (SQL Server). For information about when row-insert operations that are performed by bulk import are logged in the transaction log, see Prerequisites for Minimal Logging in Bulk Import.

[!UWAGA]

When you use OPENROWSET, it is important to understand how SQL Server handles impersonation. For information about security considerations, see Import Bulk Data by Using BULK INSERT or OPENROWSET(BULK...) (SQL Server).

Bulk Importing SQLCHAR, SQLNCHAR or SQLBINARY Data

OPENROWSET(BULK...) assumes that, if not specified, the maximum length of SQLCHAR, SQLNCHAR or SQLBINARY data does not exceed 8000 bytes. If the data being imported is in a LOB data field that contains any varchar(max), nvarchar(max), or varbinary(max) objects that exceed 8000 bytes, you must use an XML format file that defines the maximum length for the data field. To specify the maximum length, edit the format file and declare the MAX_LENGTH attribute.

[!UWAGA]

An automatically generated format file does not specify the length or maximum length for a LOB field. However, you can edit a format file and specify the length or maximum length manually.

Bulk Exporting or Importing SQLXML Documents

To bulk export or import SQLXML data, use one of the following data types in your format file.

Data type	Effect
SQLCHAR or SQLVARYCHAR	The data is sent in the client code page or in the code page implied by the collation).
SQLNCHAR or SQLNVARCHAR	The data is sent as Unicode.
SQLBINARY or SQLVARYBIN	The data is sent without any conversion.

Permissions

OPENROWSET permissions are determined by the permissions of the user name that is being passed to the OLE DB provider. To use the BULK option requires ADMINISTER BULK OPERATIONS permission.

Examples

A. Using OPENROWSET with SELECT and the SQL Server Native Client OLE DB Provider

The following example uses the SQL Server Native Client OLE DB provider to access the HumanResources.Department table in the AdventureWorks2012 database on the remote server Seattle1. (Use SQLNCLI and SQL Server will redirect to the latest version of SQL Server Native Client OLE DB Provider.) A SELECT statement is used to define the row set returned. The provider string contains the Server and Trusted_Connection keywords. These keywords are recognized by the SQL Server Native Client OLE DB provider.

SELECT a.*
FROM OPENROWSET('SQLNCLI', 'Server=Seattle1;Trusted_Connection=yes;',
     'SELECT GroupName, Name, DepartmentID
      FROM AdventureWorks2012.HumanResources.Department
      ORDER BY GroupName, Name') AS a;

B. Using the Microsoft OLE DB Provider for Jet

The following example accesses the Customers table in the Microsoft Access Northwind database through the Microsoft OLE DB Provider for Jet.

[!UWAGA]

This example assumes that Access is installed. To run this example, you must install the Northwind database.

SELECT CustomerID, CompanyName
   FROM OPENROWSET('Microsoft.Jet.OLEDB.4.0',
      'C:\Program Files\Microsoft Office\OFFICE11\SAMPLES\Northwind.mdb';
      'admin';'',Customers);
GO

C. Using OPENROWSET and another table in an INNER JOIN

The following example selects all data from the Customers table from the local instance of SQL Server Northwind database and from the Orders table from the Access Northwind database stored on the same computer.

[!UWAGA]

This example assumes that Access is installed. To run this example, you must install the Northwind database.

USE Northwind  ;
GO
SELECT c.*, o.*
FROM Northwind.dbo.Customers AS c 
   INNER JOIN OPENROWSET('Microsoft.Jet.OLEDB.4.0', 
   'C:\Program Files\Microsoft Office\OFFICE11\SAMPLES\Northwind.mdb';'admin';'', Orders)    
   AS o 
   ON c.CustomerID = o.CustomerID ;
GO

D. Using OPENROWSET to bulk insert file data into a varbinary(max) column

The following example creates a small table for demonstration purposes, and inserts file data from a file named Text1.txt located in the C: root directory into a varbinary(max) column.

USE AdventureWorks2012;
GO
CREATE TABLE myTable(FileName nvarchar(60), 
  FileType nvarchar(60), Document varbinary(max));
GO

INSERT INTO myTable(FileName, FileType, Document) 
   SELECT 'Text1.txt' AS FileName, 
      '.txt' AS FileType, 
      * FROM OPENROWSET(BULK N'C:\Text1.txt', SINGLE_BLOB) AS Document;
GO

E. Using the OPENROWSET BULK provider with a format file to retrieve rows from a text file

The following example uses a format file to retrieve rows from a tab-delimited text file, values.txt that contains the following data:

1     Data Item 1
2     Data Item 2
3     Data Item 3

The format file, values.fmt, describes the columns in values.txt:

9.0
2
1  SQLCHAR  0  10 "\t"        1  ID                SQL_Latin1_General_Cp437_BIN
2  SQLCHAR  0  40 "\r\n"      2  Description        SQL_Latin1_General_Cp437_BIN

This is the query that retrieves that data:

SELECT a.* FROM OPENROWSET( BULK 'c:\test\values.txt', 
   FORMATFILE = 'c:\test\values.fmt') AS a;

Additional Examples

For additional examples that show using INSERT...SELECT * FROM OPENROWSET(BULK...), see the following topics:

• Examples of Bulk Import and Export of XML Documents (SQL Server)

• Keep Identity Values When Bulk Importing Data (SQL Server)

• Keep Nulls or Use Default Values During Bulk Import (SQL Server)

• Use a Format File to Bulk Import Data (SQL Server)

• Use Character Format to Import or Export Data (SQL Server)

• Use a Format File to Skip a Table Column (SQL Server)

• Use a Format File to Skip a Data Field (SQL Server)

• Use a Format File to Map Table Columns to Data-File Fields (SQL Server)

Zobacz także

Odwołanie

DELETE (Transact-SQL)

FROM (Transact-SQL)

INSERT (Transact-SQL)

OPENDATASOURCE (Transact-SQL)

OPENQUERY (Transact-SQL)

Rowset Functions (Transact-SQL)

SELECT (Transact-SQL)

sp_addlinkedserver (Transact-SQL)

sp_serveroption (Transact-SQL)

UPDATE (Transact-SQL)

WHERE (Transact-SQL)

Koncepcje

Bulk Import and Export of Data (SQL Server)