mysql中建立外键注意的问题

今天在mysql建外键的时候郁闷好一阵子,每次都会蹦出msyql error number 1005
不解,,去google,搜到一篇文章

Starting from version 3.23.43b InnoDB features foreign key constraints. InnoDB is the first MySQL table type which allows you to define foreign key constraints to guard the integrity of your data.

The syntax of a foreign key constraint definition in InnoDB:

[CONSTRAINT [symbol]] FOREIGN KEY (index_col_name, ...)
                  REFERENCES table_name (index_col_name, ...)
                  [ON DELETE {CASCADE | SET NULL | NO ACTION
                              | RESTRICT}]
                  [ON UPDATE {CASCADE | SET NULL | NO ACTION
                              | RESTRICT}]

Both tables have to be InnoDB type, in the table there must be an INDEX where the foreign key columns are listed as the FIRST columns in the same order, and in the referenced table there must be an INDEX where the referenced columns are listed as the FIRST columns in the same order. InnoDB does not auto-create indexes on foreign keys or referenced keys: you have to create them explicitly. The indexes are needed for foreign key checks to be fast and not require a table scan.

为外键关联的两列都加上索引,,问题解决.

另当用mysql的客户端练mysql,在本机输入ip而不是localhost好像用root,,没有办法连上,,必须换个用户ok