Chapter 9: Configuring Character Sets, Sort Orders, and Languages

Selecting the default Unicode sort order

The default Unicode sort order is distinctly different from the sort order for the server’s default character set. This separate configuration parameter is a static parameter that requires that you restart your server and reindex the unichar data if it is changed. This sort order is identified using a string parameter, rather than a numeric parameter, to guarantee that the sort order is unique.

Table 9-6 lists the available default Unicode sort orders.

**Table 9-6: Default Unicode sort orders**
Name	ID	Description
defaultml	20	Default Unicode multi-lingual ordering
thaidict	21	Thai dictionary ordering
iso14651	22	Ordering as per ISO14651 standard
utf8bin	24	Ordering for UTF-16 that matches the UTF-8 binary
binary	25	Binary sort
altnoacc	39	Alternate accent-insensitive
altdict	45	Alternate dictionary ordering
altnocsp	46	Alternate case-insensitive with preference
scandict	47	Scandinavian dictionary ordering
scannocp	48	Scandinavian case-insensitive with preference
bin_utf8	50	UTF-8 binary sort order
dict	51	General-purpose dictionary ordering
nocase	52	General-purpose case-insensitve dictionary ordering
nocasep	53	General-purpose case-insensitve with preference
noaccent	54	General-purpose accent-insensitive dictionary ordering
espdict	55	Spanish dictionary ordering
espnocs	56	Spanish case-insensitive dictionary ordering
espnoac	57	Spanish accent-insenitive dictionary ordering
rusnocs	59	Russian case-insensitive dictionary ordering
cyrnocs	64	Cyrillic case-insensitive dictionary ordering
elldict	65	Greek dictionary ordering
hundict	69	Hungarian dictionary ordering
hunnoac	70	Hungarian accent-insensitive dictionary ordering
hunnocs	71	Hungarian case-insensitive dictionary ordering
turknoac	73	Turkish accent-insensitive dictionary ordering

Table 9-7 lists the loadable sort orders.

**Table 9-7: Loadable sort orders**
Name	ID	Description
cp932bin	129	Ordering that matches the binary ordering of CP932
dynix	130	Chinese phonetic ordering
gb3213bn	137	Ordering that matches the binary ordering of GB2312
cyrdict	140	Common cyrillic dictionary ordering
turdict	155	Turkish Dictionary ordering
euckscbn	161	Ordering that matches the binary ordering of EUCKSC
gbpinyin	163	Chinese phonetic ordering
rusdict	165	Russian dictionary ordering
sjisbin	179	Ordering that matches the binary ordering of SJIS
eucjisbn	192	Ordering that matches the binary ordering of EUCJIS
big5bin	194	Ordering that matches the binary ordering of BIG5

To view this sort order list in Adaptive Server, use sp_helpsort. See Chapter 1, “System Procedures” in the Reference Manual: Procedures for more information.

You can add sort orders using external files in the $SYBASE/collate/Unicode directory. The names and collation IDs are stored in syscharsets. The names of external Unicode sort orders do not have to be in syscharsets before you can set the default Unicode sort order.

External Unicode sort orders are provided by Sybase. Do not attempt to create external Unicode sort orders.

Sort order associated with Unicode data is completely independent of the sort order associated with traditional character data. All relational expressions involving the Unicode datatypes are performed using the Unicode sort order. This includes mixed-mode expressions involving Unicode and non-Unicode data. For example, in the following query the varchar character constant ‘Mü’ is implicitly cast to unichar and the comparison is performed according to the Unicode sort order:

select * from authors where unicode_name > 'Mü'

The same holds true for all other comparison operators, as well as the concatenation operator “+”, the operator “in”, and the operator “between.” Once again, the goal is to retain compatibility with existing database applications.

Tables joins based on equality (equijoins) deserve special mention. These are generally optimized by the server to take advantage of indexes that defined on the participating columns. When a unichar column is joined with a char column, the latter requires a conversion, and since the character sort order and the Unicode sort order are distinct, the optimizer will ignore the index on the char column.

In Adaptive Server 12.5.1, when the server’s default character set is configured to UTF-8, you can configure the server's default sort order (for char data) to be any of the above sort orders. Prior to this version, the binary sort order “bin_utf8” (ID=50) was the only well-behaved sort order for UTF-8. Although not required, the sort order for char data in UTF-8 can be selected so that it corresponds with the sort order for unichar.

There is a potential confusion regarding choice of binary sort orders for Unicode. The sort order named “binary” is the most efficient one for unichar data (UTF-16), and is thus the default. This order is based on the Unicode scalar value, meaning that all 32-bit surrogate pairs are placed after all 16-bit Unicode values. The sort order named “utf8bin” is designed to match the order of the default (most efficient) binary order for UTF-8 char data, namely “bin_utf8”. The recommended matching combinations are thus “binary” for unichar and “binary” for UTF-8 char, or “utf8bin” for unichar and “bin_utf8” for UTF-8 char. The former favors unichar efficiency, while the latter favors char efficiency. Avoid using “utf8bin” for UTF-8 char, since it is equivalent to “bin_utf8” but less efficient.

Selecting a language for system messages

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