IOS之数据库的查找，删除，添加，更新(2)

@synthesize name,ID,phone,age;
-(id)initWithName:(NSString *)aName phone:(NSString *)aPhone age:(int)aAge ID:(int)aID
{
    [super init];
   
    if (self)
    {
        self.name = aName;
        self.phone = aPhone;
        self.age = aAge;
        self.ID = aID;
       
    }
    return self;
   
}
-(NSString *)description
{
    return [NSString stringWithFormat:@"id = %d name = %@ phone = %@ age = %d",self.ID,self.name,self.phone,self.age ];
}

+(NSMutableArray *)findAll
{
    sqlite3 *db = [DB openDB];
   
    sqlite3_stmt *stmt = nil;//创建一个声明对象
   
    int result = sqlite3_prepare_v2(db, "select * from classDB order by ID ", -1, &stmt, nil);
    NSMutableArray *persons = nil;
   
    if (result == SQLITE_OK)
    {
        persons = [[NSMutableArray alloc]init];
        while (sqlite3_step(stmt) == SQLITE_ROW)
        {
            int ID = sqlite3_column_int(stmt, 0);
           
            const unsigned char *name = sqlite3_column_text(stmt, 1);
            const unsigned char *phone = sqlite3_column_text(stmt, 2);
            int age = sqlite3_column_int(stmt, 3);
           
            Person *p = [[Person alloc]initWithName:[NSString stringWithUTF8String:(const char *)name] phone:[NSString stringWithUTF8String:(const char *)phone] age:age ID:ID];
            [persons addObject:p];
            [p release];
        }
    }
    else
    {
        persons = [[NSMutableArray alloc]init];
    }
    sqlite3_finalize(stmt);
    return [persons autorelease];

   
}
+(int)count
{