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Index是不存储NULL值的，所以如果你有NULL的条件在SQL中，那么相关的索引是用不到的。CREATE TABLE PTIAN1 AS (SELECT * FROM DBA_OBJECTS); CREATE INDEX PTIAN_INDEX ON PTIAN1(DATA_OBJECT_ID); EXEC DBMS_STATS.GATHER_TABLE_STATS(\'APPS\',\'PTIAN1\', CASCADE=>TRUE );SELECT * FROM PTIAN1 WHERE DATA_OBJECT_ID = 11;SELECT * FROM PTIAN1 WHERE DATA_OBJECT_ID IS NULL;解决方法创建Function-Based Index CREATE INDEX PTIAN_FUNC_INDEX ON PTIAN1 (NVL(DATA_OBJECT_ID,-1)); E