You can use the SELECT INTO statement to export formatted data to a file.

Data Export with an SQL Query

The following query exports data into a file formatted in comma-separated values (CSV):

SELECT Id, [address-city] INTO [csv://Patient.txt] FROM [Patient] WHERE [name-use] = 'Bob'

You can specify other formats in the file URI. The possible delimiters are tab, semicolon, and comma with the default being a comma. The following example exports tab-separated values:

SELECT Id, [address-city] INTO [csv://Patient.txt;delimiter=tab] FROM [Patient] WHERE [name-use] = 'Bob'

C#

String connectionString = "URL=http://test.fhir.org/r4b/;ConnectionType=Generic;ContentType=JSON;AuthScheme=None;";

using (FHIRConnection connection = new FHIRConnection(connectionString)) {
  FHIRCommand cmd = new FHIRCommand("SELECT Id, [address-city] INTO [csv://Patient.txt] FROM [Patient] WHERE [name-use] = 'Bob' ", connection);
  int rowsAffected = cmd.ExecuteNonQuery();
} 

VB.NET

Dim connectionString As [String] = "URL=http://test.fhir.org/r4b/;ConnectionType=Generic;ContentType=JSON;AuthScheme=None;" 

Using connection As New FHIRConnection(connectionString)
  Dim cmd As New FHIRCommand("SELECT Id, [address-city] INTO [csv://Patient.txt] FROM [Patient] WHERE [name-use] = 'Bob'", connection)
  Dim rowsAffected As Integer = cmd.ExecuteNonQuery()
End Using

You can specify other file formats in the URI. The following example exports tab-separated values:

C#

String connectionString = "URL=http://test.fhir.org/r4b/;ConnectionType=Generic;ContentType=JSON;AuthScheme=None;";

using (FHIRConnection connection = new FHIRConnection(connectionString)) {
  FHIRCommand cmd = new FHIRCommand("SELECT * INTO [Patient] IN [csv://filename=c:/Patient.csv;delimiter=tab] FROM [Patient] WHERE [name-use] = 'Bob'", connection);
  int rowsAffected = cmd.ExecuteNonQuery();
} 

VB.NET

Dim connectionString As [String] = "URL=http://test.fhir.org/r4b/;ConnectionType=Generic;ContentType=JSON;AuthScheme=None;" 

Using connection As New FHIRConnection(connectionString)
  Dim cmd As New FHIRCommand("SELECT * INTO [Patient] IN [csv://filename=c:/Patient.csv;delimiter=tab] FROM [Patient] WHERE [name-use] = 'Bob'", connection)
  Dim rowsAffected As Integer = cmd.ExecuteNonQuery()
End Using