GB18030 is a separate standard used in the People's Republic of China for encoding Chinese characters. In GB18030, characters can be 1, 2, or 4 bytes. SQL Server provides support of GB18030-encoded characters by recognizing them when they enter the server from a client-side application, and converting and storing them natively as Unicode characters. After they are stored in the server, they are treated as Unicode characters in any subsequent operations performed on them.
When you use GB18030 characters, remember that these characters can be used in ordering and comparison operations, but when you use a collation version older than SQL Server 90, comparisons are only based on their code points and not on other linguistically meaningful ways. Therefore, you should be careful when you use GB18030 characters in operations such as ORDER BY, GROUP BY, and DISTINCT, and especially when GB18030 and non-GB18030 characters are included in the same operation. To enable meaningful string comparisons that use GB18030 characters, use the new SQL Server 90 collation version, signified by the 90 suffix added to its name. For example, instead of the Chinese_PRC collation, use Chinese_PRC_90. For more information, see Collation Settings in Setup.
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