Oracle排序的编码问题

 

Oracle9i之前，中文是按照二进制编码进行排序的。在oracle9i中新增了按照拼音、部首、笔画排序功能。设置NLS_SORT值 SCHINESE_RADICAL_M 按照部首（第一顺序）、笔划（第二顺序）排序 SCHINESE_STROKE_M 按照笔划（第一顺序）、部首（第二顺序）排序 SCHINESE_PINYIN_M 按照拼音排序，系统的默认排序方式为拼音排序

NLS_SORTProperty Description Parameter type String Syntax NLS_SORT = { BINARY | linguistic_definition } Default value Derived from NLS_LANGUAGE Modifiable ALTER SESSION Range of values BINARY or any valid linguistic definition name

NLS_SORT specifies the collating sequence for ORDER BY queries.

If the value is BINARY, then the collating sequence for ORDER BY queries is based on the numeric value of characters (a binary sort that requires less system overhead).

If the value is a named linguistic sort, sorting is based on the order of the defined linguistic sort. Most (but not all) languages supported by the NLS_LANGUAGE parameter also support a linguistic sort with the same name.

Note:

Setting NLS_SORT to anything other than BINARY causes a sort to use a full table scan, regardless of the path chosen by the optimizer. BINARY is the exception because indexes are built according to a binary order of keys. Thus the optimizer can use an index to satisfy the ORDER BY clause when NLS_SORT is set to BINARY. If NLS_SORT is set to any linguistic sort, the optimizer must include a full table scan and a full sort in the execution plan. You must use the NLS_SORT operator with comparison operations if you want the linguistic sort behavior.