oracle全文索引之停用词的通配符功能
全文索引停用词的设置在前面的文章中已经介绍过了，这里简单说明记录一下停用词在查询时候需要注意的地方。
Oracle10g中，如果安装语言为中文，默认的LEXER为CHINESE_VGRAM_LEXER，默认的停用词语言也为中文。这篇通过对比中文环境和英文环境来说明停用词查询的一些特点。
SQL> show user
USER is "MYUSER"
SQL> CREATE TABLE T (ID NUMBER, DOCS VARCHAR2(1000));
Table created.
SQL> INSERT INTO T VALUES (1, 'This example test stopword.');
1 row created.
SQL> INSERT INTO T VALUES (2, 'Oracle9i chinese language environment default stopword are english.');
1 row created.
SQL> COMMIT;
Commit complete.
SQL> CREATE INDEX IND_T_DOCS ON T(DOCS) INDEXTYPE IS CTXSYS.CONTEXT;
Index created.
SQL> SELECT * from T WHERE CONTAINS(DOCS, 'This') > 0;
no rows selected
英文环境下允许单独查询停用词，但是不会返回结果。
SQL> SELECT * from T WHERE CONTAINS(DOCS, 'are english') > 0;
ID DOCS
--- --------------------------------------------------
2 Oracle9i chinese language environment default stop
word are english.
SQL> SELECT * from T WHERE CONTAINS(DOCS, 'is english') > 0;
ID DOCS
--- --------------------------------------------------
2 Oracle9i chinese language environment default stop
word are english.
SQL> SELECT * from T WHERE CONTAINS(DOCS, 'stopword are english') > 0;
ID DOCS
--- --------------------------------------------------
2 Oracle9i chinese language environment default stop
word are english.
SQL> SELECT * from T WHERE CONTAINS(DOCS, 'stopword is english') > 0;
ID DOCS
--- --------------------------------------------------
2 Oracle9i chinese language environment default stop
word are english.
SQL> SELECT * from T WHERE CONTAINS(DOCS, 'are stopword') > 0;
ID DOCS
--- --------------------------------------------------
1 This example test stopword.
2 Oracle9i chinese language environment default stop
word are english.
SQL> SELECT * from T WHERE CONTAINS(DOCS, '
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