Is it possible to bulk insert data into a table that has columns encrypted with Always Encrypted?

Question

In SSMS we are attempting to bulk insert from a csv file into a table that has a column encrypted using SQL Server 2016's Always Encrypted feature.

This is the command we're using:

INSERT INTO membersE
SELECT *
FROM OPENROWSET(
    BULK 'c:\members.csv', 
    FORMATFILE = 'c:\membersEFormat.xml',
    FIRSTROW = 2
    ) m

This returns the typical error you get when attempting to insert into an encrypted column:

Msg 206, Level 16, State 2, Line 6
Operand type clash: varbinary is incompatible with varchar(50) encrypted with (encryption_type = 'DETERMINISTIC', encryption_algorithm_name = 'AEAD_AES_256_CBC_HMAC_SHA_256', column_encryption_key_name = 'CEK_Auto1', column_encryption_key_database_name = 'DATABASE') collation_name = 'Latin1_General_BIN2'

We understand that you can't insert into an encrypted column via SSMS and that you need to use a .NET 4.6.1+ client, but we'd like to know if bulk insert operations are not possible as well?

SAMPLE CODE THAT WORKED FOR ME
(to satisfy Windows10's request)

        SqlCommand cmd;
        SqlConnection conn;
        SqlBulkCopy copy;
        SqlDataAdapter da;
        DataTable dt;

        using (conn = new SqlConnection(ConfigurationManager.ConnectionStrings["Database"].ConnectionString))
        {
            conn.Open();

            using (cmd = new SqlCommand("SELECT * FROM members", conn))
            using (copy = new SqlBulkCopy(conn))
            using (da = new SqlDataAdapter(cmd))
            using (dt = new DataTable())
            {
                cmd.CommandTimeout = 600;

                da.Fill(dt);

                cmd.CommandText = "TRUNCATE TABLE membersE";
                cmd.ExecuteNonQuery();

                copy.DestinationTableName = "membersE";
                copy.WriteToServer(dt);                    
            }
        }

Answer 1

Bulk Insert operations in the manner you are describing are not supported for encrypted column via SSMS.

Please refer to this (https://blogs.msdn.microsoft.com/sqlsecurity/2015/07/28/encrypting-existing-data-with-always-encrypted/) article to migrate your existing data to Always Encrypted

Also, please note that doing bulk inserts through a C# (.NET 4.6.1+ client) app is supported.

You can do this in c# using SqlBulkCopy specifically using SqlBulkCopy.WriteToServer(IDataReader) Method. I am assuming you are trying to load data from csv file to a table with encrypted column (say encryptedTable). I would do the following

• Create a new table (say unencryptedTable, for security purposes, you might consider creating this table in a local sql server instance) with the same schema without any column encryption.
• Load the csv data into unencryptedTable, using the method that you described in the question
• Do select * from unencryptedTable to load the data in a SqlDataReader then use SqlBulkCopy to load it to the encryptedTable using SqlBulkCopy.WriteToServer(IDataReader) Method

If you have additional questions regarding this, please post questions in the comment section and I will try my best to address them :)

Answer 2

A simpler method that worked for us was to:

1. Import the CSV using either the method you mentioned or through an SSMS Task, but to a new table.
2. Encrypt the column on the new table so the column data types match between the new and existing tables.
3. Perform an INSERT INTO ... SELECT FROM ... query to insert from the new table to the existing table.
4. Drop the new table.