Can Binary Strings Be Converted into Unicode Character Strings in SQL Server Transact-SQL?

Can binary strings be converted into Unicode character strings? The answer is yes. But you need to know how Unicode characters are represented in a binary format. Remember the following simple rules:

• An ASCII character is stored in 1 byte.
• A Unicode character is stored in 2 bytes.
• When an ASCII character is mapped to a Unicode character, the first type equals to the same code value as the ASCII character, and the second type equals to 0x00.

The tutorial exercise below shows you some interesting conversion behaviors:

-- 1. Binary representation of ASCII characters 
SELECT CONVERT(VARBINARY(40),'FYIcenter.com');
GO
0x46594963656E7465722E636F6D

-- 2. Binary representation of Unicode characters 
SELECT CONVERT(VARBINARY(40),N'FYIcenter.com');
GO
0x460059004900630065006E007400650072002E0063006F006D00

-- 3. Converting a binary string back to Unicode characters
SELECT CONVERT(NVARCHAR(40),
   0x460059004900630065006E007400650072002E0063006F006D00);
GO
FYIcenter.com

-- 4. Converting a binary string back to ASCII characters
SELECT CONVERT(VARCHAR(40),
   0x460059004900630065006E007400650072002E0063006F006D00);
GO
F

-- 5. Converting a binary string back to Unicode characters
SELECT CONVERT(NVARCHAR(40),0x46594963656E7465722E636F6D);
GO
??????m

-- 6. Converting a binary string back to ASCII characters
SELECT CONVERT(VARCHAR(40),0x46594963656E7465722E636F6D);
GO
FYIcenter.com

Test 4 seems to be giving a wrong result. It should be something like "F Y I c e n t e r . c o m ". But the client tool does not know how to display the 0x00 ASCII character and stops showing the rest of the characters.

Result of test 5 shows real characters on the SQL Server Management Studio windows. But they can not be represented on this Web page, because it is not set to handle Unicode characters. This is why you see (?) characters.

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