mysql的char数据类型和varchar数据类型的选择_MySQL
mysql的char数据类型和varchar数据类型的选择
存储引擎对于选择char和varchar的影响：
对于MyISAM存储引擎：最好使用固定长度的数据列代替可变长度的数据列。这样可以使整个表静态化，从而使数据检索更快，用空间换时间
对于InnoDB存储引擎：使用可变长度的数据列，因为InnoDB数据表的存储格式不分固定长度和可变长度，因此使用char不一定比使用
varchar更好，但由于varchar是按照实际的长度存储，比较节省空间，所以对磁盘I/O和数据存储总量比较好
mysql并没有sqlserver的nchar和nvarchar数据类型
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