使用索引的误区之二：使用了 和 != 操作符，导致查询不使用索引[2]

|*  1 |  table access full   | emp         |       |       |       |

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predicate information (identified by operation id):

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   1 - filter("emp"."empno"<>10)

note: rule based optimization

14 rows selected

将上面的查条件“empno <>10”转换成“empno <10 and empno>10”后，就可以使用索引了

select empno from emp where empno <10 and empno>10;

plan_table_output

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