sqlserver2008中遇到一个坑爹的问题，使用以下语句添加的数据
insert into testtable (
username,
password,
productcode
)
select 'testname',
ENCRYPTBYPASSPHRASE(
'test passphrase',
'testpassword'
), 'productcode'
竟然不能用以下查询语句解出
SELECT t.id as id, t.username as username, t.password as password, t.productcode as productcode FROM (
SELECT id, username,
CAST(DECRYPTBYPASSPHRASE( 'test passphrase', password ) as varchar(20))
as password, productcode
FROM testtable
) t
WHERE t.username='testname'
而当使用了nvarchar时却能够成功做到
SELECT t.id as id, t.username as username, t.password as password, t.productcode as productcode FROM (
SELECT id, username,
CAST(DECRYPTBYPASSPHRASE( 'test passphrase', password ) as nvarchar(20))
as password, productcode
FROM testtable
) t
WHERE t.username='testname'