The OPENROWSET function in SQL Server allows you to access remote data sources directly from a SQL query, leveraging the concept of adhoc distributed queries. This can be particularly useful for accessing data from other databases (even if they are not linked servers), flat files, or other external data sources.
Here's how to use OPENROWSET to access data from a remote data source:
Syntax
The basic syntax of OPENROWSET is as follows:
OPENROWSET ( 'provider_name', 'datasource'; 'user'; 'password', 'query' )
Steps to Use OPENROWSET
1. Specify the Provider: This can be an OLE DB provider that corresponds to the type of data you are accessing. Common providers include:
- SQLNCLI for SQL Server
- Microsoft.ACE.OLEDB.12.0 for Access
- MSDASQL for ODBC data sources
2. Data Source: This is the name of the server or file from which you're fetching the data.
3. Credentials: If required, you provide the username and password. You can also use trusted connections depending on the setup.
4. The Query: This is the actual SQL query to be executed against the remote data source.
Example
Here is a simple example that shows how to use OPENROWSET to access data from a SQL Server database:
SELECT *
FROM OPENROWSET('SQLNCLI',
'Server=RemoteServerName;Database=RemoteDatabaseName;UID=UserName;PWD=Password',
'SELECT * FROM RemoteTableName')
In this example:
- SQLNCLI is the provider.
- RemoteServerName is the address of the remote SQL Server.
- RemoteDatabaseName is the database you wish to query.
- UserName and Password are the credentials to access the database.
- The query 'SELECT * FROM RemoteTableName' retrieves data from the specified table.
Important Notes
- Permissions: Ensure that the database settings allow for the use of OPENROWSET. The server needs to be configured to allow ad-hoc distributed queries.
- Linked Servers: If you're frequently accessing remote data, consider setting up a linked server for easier access.
- Security: Be careful with credentials and using OPENROWSET in production environments, as passwords in the query can expose sensitive information.