主要还是在数据库内容同步的时候遇到的问题，服务器端也不标识变化发生，那客户端用sqilite3,本来就是要实现目的，udpate不成功，我就用insert。

自然想到去拿那个影响的record数目。

但看来大家多推荐replace，这个replace是不是要知道原来sql的primarykey的值啊，可我偷懒，没设置，全用了一个自增长的id，这下。。。

因为数据库建表时没有指定primary key,所以replace语句不正常.

option 1 would look like: ／／基本来说，目前的数据结构，表，应该可以做到用replace or insert。。。。。

NSString * update =[NSString stringWithFormat:@"INSERT OR REPLACE INTO LIST (COUNT,NAME,DATE,IDNUM) VALUES (?,?,?)"]; 

option 2 would look like: ／／至于效率问题，我们需要找个同学测试下。。。。

"SELECT * FROM LIST WHERE IDNUM = '%i'",accessID integerValue]]; sqlite3_stmt stmt; int rc  sqlite3_prepare_v2(db[ UTF8String],0)"> -1& nil);ifrc == sqlITE_OK){   sqlite3_step sqlITE_ROW     "UPDATE LIST SET COUNT = ?,NAME = ?,DATE = ?,IDNUM = ? WHERE IDNUM = '%i'"   }else    }

为了减少网络流量，请问我可以只拿房间GUID和状态两个字段么，呵呵。。。。

The MIN/MAX optimization＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝

Queries of the following forms will be optimized to run in logarithmic time assuming appropriate indices exist:

  SELECT MIN(x) FROM table;
  SELECT MAX(x) FROM table;

In order for these optimizations to occur,they must appear in exactly the form shown above - changing only the name of the table and column. It is not permissible to add a WHERE clause or do any arithmetic on the result. The result set must contain a single column. The column in the MIN or MAX function must be an indexed column.

select max(dd) as x,min(dd) as y fromddwhere state=4／／本来测试没有看where，后来用了where发现不对了。这。。。。！