Encryption/decryption with an asymmetric key is very costly compared to encryption/decryption with a symmetric key. We do not recommend using an asymmetric key when you work with large datasets, such as user data in tables.
The following example decrypts ciphertext that was encrypted with asymmetric key JanainaAsymKey02, which was stored in AdventureWorks2008R2.ProtectedData04. The returned data is decrypted using asymmetric key JanainaAsymKey02, which has been decrypted with password pGFD4bb925DGvbd2439587y. The plaintext is converted to type nvarchar.
ProtectedData, N'pGFD4bb925DGvbd2439587y' ))
WHERE Description = N'encrypted by asym key''JanainaAsymKey02''';