通过对称密钥加密

-- Create the key and protect it with the cert
CREATE SYMMETRIC KEY My_Sym_Key
WITH ALGORITHM = AES_256  
ENCRYPTION BY CERTIFICATE My_New_Cert;
GO

-- open the key
OPEN SYMMETRIC KEY My_Sym_Key
DECRYPTION BY CERTIFICATE My_New_Cert;

-- Encrypt
SELECT EncryptByKey(Key_GUID('SSN_Key_01'), 'This text will get encrypted');