--在 Microsoft SQL Server 的未来版本中将删除 ntext、text 和 image 数据类型
DECLARE @t table(id int identity,jj ntext)
INSERT @t SELECT N'test'
UNION ALL SELECT N'test1'
--display all
SELECT * FROM @t
--error
--SELECT * FROM @t WHERE jj='test'
--ok
SELECT * FROM @t where CAST(jj as NVARCHAR(4000))='test'
--it will be string type in .Net When meeting varchar,nvarchar,ntext