请参考以下 参见MS Transact-SQL Help Unicode Character Strings ncharFixed-length Unicode data with a maximum length of 4,000 characters. nvarcharVariable-length Unicode data with a maximum length of 4,000 characters. sysname is a system-supplied user-defined data type that is functionally equivalent to nvarchar(128) and is used to reference database object names.ntextVariable-length Unicode data with a maximum length of 2^30 - 1 (1,073,741,823) characters.
如果用CHAR或者VARCHAR类型，只能达到8000，但没有人会这么用！
参见MS Transact-SQL Help
Unicode Character Strings
ncharFixed-length Unicode data with a maximum length of 4,000 characters. nvarcharVariable-length Unicode data with a maximum length of 4,000 characters. sysname is a system-supplied user-defined data type that is functionally equivalent to nvarchar(128) and is used to reference database object names.ntextVariable-length Unicode data with a maximum length of 2^30 - 1 (1,073,741,823) characters.