下面是我做的测试~索引是个复合索引

都是索引扫描没问题的

scott@CCDB> select * from salgrade;

GRADE      LOSAL      HISAL

---------- ---------- ----------

1        700       1200

2       1201       1400

3       1401       2000

4       2001       3000

5       3001       9999

scott@CCDB> select * from salgrade where 2222 between LOSAL and HISAL;

GRADE      LOSAL      HISAL

---------- ---------- ----------

4       2001       3000

Execution Plan

----------------------------------------------------------

Plan hash value: 3196158779

----------------------------------------------------------------------------------------

| Id  | Operation                   | Name     | Rows  | Bytes | Cost (%CPU)| Time     |

----------------------------------------------------------------------------------------

|   0 | SELECT STATEMENT            |          |     4 |    40 |     2   (0)| 00:00:01 |

|   1 |  TABLE ACCESS BY INDEX ROWID| SALGRADE |     4 |    40 |     2   (0)| 00:00:01 |

|*  2 |   INDEX RANGE SCAN          | LH_INDEX |     4 |       |     1   (0)| 00:00:01 |

----------------------------------------------------------------------------------------

Predicate Information (identified by operation id):

---------------------------------------------------

2 - access("HISAL">=2222 AND "LOSAL"<=2222)

filter("HISAL">=2222)

Statistics

----------------------------------------------------------

1  recursive calls

0  db block gets

3  consistent gets

0  physical reads

0  redo size

656  bytes sent via SQL*Net to client

520  bytes received via SQL*Net from client

2  SQL*Net roundtrips to/from client

0  sorts (memory)

0  sorts (disk)

1  rows processed

我建议在SERVER端的SQLPLUS  用trace在试试看，要不就看看统计信息