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create talbe if not exsits disk.t_directories
(
id int(11) not null auto_increment,
user varchar(25) not null,
path varchar(255) not null,
parent_path varchar(255) not null,
dir varchar(20) not null,
create_time datetime not null,
primary key(id),
unique key user (user,path)
)engine=InnoDB default charset=utf8 collate=utf8_unicode_ci;
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create_definition:
  col_name column_definition
  | [CONSTRAINT [symbol]] PRIMARY KEY [index_type] (index_col_name,...)
  [index_option] ...
  | {INDEX|KEY} [index_name] [index_type] (index_col_name,...)
  [index_option] ...
| [CONSTRAINT [symbol]] UNIQUE [INDEX|KEY]
[index_name] [index_type] (index_col_name,...)
[index_option] ...
  | {FULLTEXT|SPATIAL} [INDEX|KEY] [index_name] (index_col_name,...)
  [index_option] ...
  | [CONSTRAINT [symbol]] FOREIGN KEY
  [index_name