关于ORACLE怎么走索引?
大家好:
表Person有字段 businessNo和taskId
现在已经对businessNo新建索引index_businessNo,也对taskId新建了索引taskId_index
如果根据businessNo和taskId查询Person表
select * from Personwhere businessNo=? and taskId=?
能否在index_businessNo和taskId_index已经存在的索引基础上,对businessNo和index_businessNo新建多列唯一索引index_businessNo_taskId
假如能够对businessNo和taskId新建多列唯一索引,
那么查询select * FROM PersonWHERE businessNo=? 走的index_businessNo还是index_businessNo_taskId ?
谢谢大家!