Чрезвычайно маловероятно, что ваша база данных будет содержать какую-либо таблицу или другой объект с идентификатором с этим символом. При этом, это может быть сделано.
Я использовал SQL Server 2008 для запуска следующего скрипта:
create database TestFFFF
go
alter database TestFFFF set compatibility_level = 80
go
use TestFFFF
declare @s nvarchar(200)
-- Build a string that will create a table
-- In our first example, we'll use a simple character
-- nchar(65) is the same as capital letter 'A'
-- so this will create a table named tungnAguyen.
set @s = N'create table [tungn' + NCHAR(65) + N'guyen] ( IDA int )'
exec sp_executesql @s
-- Now we will create a table name with character U+FFFF.
-- Note 65535 is decimal for hexadecimal FFFF.
-- Note this will only work if the database compatibility level is 80 or less.
-- Otherwise you'll get an error message.
set @s = N'create table [tungn' + NCHAR(65535) + N'guyen] ( IDF int )'
exec sp_executesql @s
-- Let's see if it worked.
-- I'll convert the table name to hexadecimal so you can see each character.
select name, CAST(name as varbinary(1000)) as BinName
from sysobjects where name like N'tun%'
-- The result looks like this:
-- name BinName
-- tungnAguyen 0x740075006E0067006E00410067007500790065006E00
-- tungnguyen 0x740075006E0067006E00FFFF67007500790065006E00
--
-- The first row shows the first table we created using letter 'A'.
-- In the hexidecimal version you see 4100 in the middle. That's the 'A'
--
-- In the second row, there appears to be nothing in the middle
-- of the name.
-- The reason is that character FFFF is not printable.
-- In the middle of the hexidecimal you see FFFF. This is proof
-- that the identifier contains that character.
--
-- Let's see if we can access these tables.
-- Start with the table that contains letter 'A'
set @S = N'select * from [tungn' + NCHAR(65) + N'guyen]'
exec sp_executesql @S
-- It works.
-- We've not inserted any rows, so the result is empty, but it works.
-- Now let's access the other table.
set @S = N'select * from [tungn' + NCHAR(65535) + N'guyen]'
exec sp_executesql @S
-- This works too, as long as we are using compatibility level 80.
-- Let's change the compatibility level to 90
-- and see what happens.
go
alter database TestFFFF set compatibility_level = 90
go
declare @S nvarchar(200)
set @S = N'select * from [tungn' + NCHAR(65535) + N'guyen]'
exec sp_executesql @S
-- This time it fails. We get an error message:
-- Msg 1055, Level 16, State 1, Line 73
-- 'tun...' is an invalid name because it contains
-- a NULL character or an invalid unicode character.
--
-- The U+FFFF is the invalid Unicode character it is talking
-- about. According to the Unicode standard there is
-- no such character.