优化转换:

  1. OR 转换:T.C = exprOR 连接子句转换为 IN 子句(x IN (expr1, expr2, expr3)),可利用索引优化。

  2. BETWEEN 转换:BETWEEN 子句转换为等价的子句((a BETWEEN b AND c) AND (a >= b) AND (a <= c)),可利用索引优化。