SQL Server Linked Server

Query from link server

for default instance name

SELECT * FROM [LinkServerName].DatabaseName.dbo.TableName

SELECT * FROM OPENQUERY([LinkServerName], 'SELECT * FROM TableName')

for other instance name

SELECT * FROM [LinkServerName\InstanceName].DatabaseName.dbo.TableName

SELECT * FROM OPENQUERY([LinkServerName\InstanceName], 'SELECT * FROM TableName')

other method

SELECT * FROM LinkServerName..UserName.TableName