主键是否在MySQL中自动索引？
问题描述：
您需要显式创建索引，还是在定义主键时是隐式的？答案是相同的MyISAM和InnoDB？
Do you need to explicitly create an index, or is it implicit when defining the primary key? Is the answer the same for MyISAM and InnoDB?
答
主键索引始终。这是为MyISAM和InnoDB相同的，并且通常是为所有的存储引擎，在所有支持指数真
The primary key is always indexed. This is the same for MyISAM and InnoDB, and is generally true for all storage engines that at all supports indices.