What is an Openrowset SQL server?

 OPENROWSET is a function in SQL Server that allows you to access remote data sources directly without needing to set up linked servers. It provides a way to query data from external sources, such as another SQL Server, an Excel file, or other OLE DB-compliant data sources, within a query.

The OPENROWSET function can be used in several scenarios:

1. Accessing Data from External Databases: You can query data from a remote server or database, even if it's not linked, using the proper credentials and connection string.

2. Reading Data from Files: It can be used to read data from files like CSV, Excel, or other file formats supported by OLE DB providers.

3. Importing or Exporting Data: You can use OPENROWSET to import data into SQL Server or export data from SQL Server to external files.

Syntax

SELECT * FROM OPENROWSET('provider_name', 'connection_string', 'query');

• provider_name: The OLE DB provider to use (e.g., SQLNCLI11 for SQL Server).
• connection_string: The connection details for the external data source (such as server name, database name, and authentication credentials).
• query: The query to run against the external data source.

Example 1: Accessing Data from Another SQL Server

SELECT * 
FROM OPENROWSET('SQLNCLI', 
                'Server=remote_server_name;Trusted_Connection=yes;',
                'SELECT * FROM remote_database.dbo.some_table');

Example 2: Accessing Data from an Excel File

SELECT * 
FROM OPENROWSET('Microsoft.ACE.OLEDB.12.0', 
                'Excel 12.0;Database=C:\path\to\file.xlsx;', 
                'SELECT * FROM [Sheet1$]');

Important Considerations:

• Security: To use OPENROWSET, the SQL Server must be configured to allow Ad Hoc Distributed Queries, and the necessary permissions must be set on the external data source.
• Performance: While OPENROWSET is convenient, queries that involve external sources can be slower than working with local SQL Server data, especially over a network.
• Configuration: In some environments, such as in a SQL Server instance hosted on Azure or certain security configurations, OPENROWSET might require additional setup or may be disabled.

In summary, OPENROWSET is a versatile function in SQL Server that enables querying of external data sources without the need for permanent linked server configurations.