iphone - iPhone中的Select语句崩溃问题

Question

-(void)insertDataToFavourites:(int)pageid :(NSString *)description
{
    sqlite3_stmt *insertStatement = nil;
    NSString *sql;
    int returnvalue;

    sql = [NSString stringWithFormat:@"insert into AddFavorite (Id,Description) VALUES (?,?)"];

    returnvalue = sqlite3_prepare_v2(database, [sql UTF8String], -1, &insertStatement, NULL);

    if (returnvalue == 1){
        NSAssert1 (0,@"Error: failed to prepare statement with message '%s'.", sqlite3_errmsg(database));
    }
    sqlite3_bind_text(insertStatement, 2,[[tempDict objectForKey:@"pageid"] UTF8String], -1, SQLITE_TRANSIENT);
    sqlite3_bind_text(insertStatement, 3,[[tempDict objectForKey:@"desc"] UTF8String], -1, SQLITE_TRANSIENT);
    if (SQLITE_DONE != sqlite3_step(insertStatement)){
        NSAssert1(0, @"Error while inserting data. '%s'", sqlite3_errmsg(database));
    }
    else{
        sqlite3_reset(insertStatement);
    }

    sqlite3_finalize(insertStatement);

    if(sqlite3_exec(database, [sql UTF8String], NULL, NULL, NULL) != SQLITE_DONE ){
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Alert!" message:@"Data saved Successfully." delegate:self cancelButtonTitle:@"Ok" otherButtonTitles:nil, nil];
        [alert show];
        [alert release];
    }

    else{
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Alert!" message:@"Data insertion error." delegate:self cancelButtonTitle:@"Ok" otherButtonTitles:nil, nil];
        [alert show];
        [alert release];
    }

}

上面的代码我正在将数据插入到 Sqlite 数据库表中。这向我显示警报数据已成功保存。 将数据插入收藏夹列表时。

-(void)getFavoriteList
{

    if([ArrFav count] > 0)
        [ArrFav removeAllObjects];

    ArrFav = [[NSMutableArray alloc] init];

    sqlite3_stmt *selectStatement=nil;  
    NSString *sql;
    int returnvalue;

    sql=[NSString stringWithFormat:@"SELECT Description FROM AddFavorite"];

    returnvalue = sqlite3_prepare_v2(database, [sql UTF8String], -1, &selectStatement, NULL);

    if(returnvalue==1)
    {
        NSAssert1(0, @"Error: failed to select the database with message '%s'.", sqlite3_errmsg(database));
    }

    NSMutableDictionary *dict;
    NSString *str;
    if(returnvalue == SQLITE_OK)
    {                       
        while(sqlite3_step(selectStatement) == SQLITE_ROW)
        {   
            dict = [[NSMutableDictionary alloc] init];
            [dict setObject:[NSString stringWithUTF8String:(char *)sqlite3_column_text(selectStatement,1)] forKey:@"Description"];

            [ArrFav addObject:[dict objectForKey:@"Description"]];
            NSLog(@"Favorite data is:--> %@",ArrFav);
        }       
    }
}

这是从sqlite数据库表中选择数据的代码。在行 [dict setObject:[NSString stringWithUTF8String:(char *)sqlite3_column_text(selectStatement,1)] forKey:@"Description"]; 应用程序崩溃了。

任何人都可以建议我解决这个问题，为什么会出现这个问题以及解决方案是什么？

Answer 1

我认为您正在尝试为字典中的键设置零值。这意味着您没有从 SELECT 语句中获得任何结果。请使用 Mozilla sqlite 编辑器检查数据库的内容，并查看您尝试检索的值是否存在于数据库中。