JOIN查询无法在iphone设备中工作，但在iOS模拟器中工作

Question

我有2个表资源， ResourceViewHistory 资源包括以下字段： ResourceId ， TypeId ，名称，网址， IsFavorite ，的语言代码下，的类别ID 即可。 ResourceViewHistory包含以下字段： ViewId ， ResourceId ， DateViewed ，经度，纬度 < / p>

我想在Resources表中为ResourceId设置结果集：ResourceViewHistory表中相同ResourceId的Name，Url，IsFavorite，ResourceId和DateViewed，Longitude，Latitude以及CategoryId = 1，TypeId = 1

我的查询是：

SELECT r.ResourceId,Url,Name,IsFavorite,max(v.DateViewed) AS LastVisited,Longitude,Latitude 
FROM Resources r 
LEFT JOIN ResourceViewHistory v  on (r.ResourceId=v.ResourceId) 
WHERE CategoryId=1 AND TypeId=1 
GROUP BY r.ResourceId

以上查询在模拟器中工作但在iPhone设备中不起作用。我的ObjectiveC代码如下.arrUrlDetails数组总是显示0个对象

+(NSMutableArray*)getUrlDetails{
NSString *strHome = NSHomeDirectory();
NSString *strDestPath = [NSString stringWithFormat:@"%@/Documents/test.sqlite",strHome];

NSMutableArray *arrUrlDetails=[[NSMutableArray alloc]init];
sqlite3 *db;
int n = sqlite3_open([strDestPath UTF8String], &db);
if (n==SQLITE_OK) {
    NSString *strQuery=@"SELECT r.ResourceId,Url,Name,IsFavorite,max(v.DateViewed) AS LastVisited,Longitude,Latitude FROM Resources r LEFT JOIN ResourceViewHistory v  on (r.ResourceId=v.ResourceId) where CategoryId=1 AND TypeId=1 group by r.ResourceId";
    sqlite3_stmt *stmt;
    const char *err_msg;

    int res=sqlite3_prepare_v2(db, [strQuery UTF8String], -1, &stmt, &err_msg);
    if (res == SQLITE_OK) {
        while (sqlite3_step(stmt)==SQLITE_ROW) {


            Resources *resources=[[Resources alloc]init];
            resources.resourceId=sqlite3_column_int(stmt,0);
            resources.name=[NSString stringWithUTF8String:(char *) sqlite3_column_text(stmt, 2)];
            resources.url=[NSString stringWithUTF8String:(char *) sqlite3_column_text(stmt, 1)];
            resources.isFavorite=[NSString stringWithUTF8String:(char *) sqlite3_column_text(stmt, 3)];
            resources.dateViewed=[NSString stringWithUTF8String:(char *) sqlite3_column_text(stmt, 4)];
            resources.latitude=sqlite3_column_double(stmt, 6);

            [arrUrlDetails addObject:resources];

        }
    }

}

return arrUrlDetails;

}