mysql Error Code

• Error Code: 1071. Specified key was too long; max key length is 767 bytes
  -对于mysql的key（primary foreign unique）在InnoDB中有最大767 bytes的约束
  -参考说明

create table TTT(    id   VARCHAR(1000) primary key -- 报错);create table TTT(    id   VARCHAR(191) primary key -- VARCHAR(192)就不能建表)CHARSET=utf16;

• SQLErrorCode: 1248 Every derived table must have its own alias.
  -子查询生成的表要有别名