mysql条件应用or查询不会触发索引

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mysql> explain select * from emp where ename="dsleos" or ename="saesad" \G<br />
*************************** 1. row ***************************<br />
           id: 1<br />
  select_type: SIMPLE<br />
        table: emp<br />
         type: range<br />
possible_keys: e_i<br />
          key: e_i<br />
      key_len: 62<br />
          ref: NULL<br />
         rows: 2<br />
        Extra: Using where<br />
1 row in set (0.00 sec)<br />