text: 
  -- 注意,每条sql语句必须独占一行,否则会出错.
  CREATE TABLE comment_temp (
  	Id	INTEGER PRIMARY KEY AUTOINCREMENT,
  	customField	TEXT,
  	_id	TEXT UNIQUE,
  	createTime	TEXT,
  	feedId	TEXT,
  	nextPageUrl	TEXT,
  	text	TEXT);
  
  INSERT INTO comment_temp SELECT Id,customField,_id,createTime,feedId,nextPageUrl,text FROM comment;
  DROP TABLE comment ;
  ALTER TABLE comment_temp RENAME TO comment ;
  
  ALTER TABLE user  ADD isFollowed INTEGER ;
  ALTER TABLE feeditem  ADD forwardCount INTEGER ;
  ALTER TABLE feeditem  ADD isLiked INTEGER ;
  ALTER TABLE feeditem  ADD shareLink TEXT ;
  ALTER TABLE feeditem  ADD category TEXT ;
  