sqlite3和fmdb嵌套的FMResultSet是可能的吗？

Question

我正在尝试通过一个主要的细节表来迭代,我想在我去的时候填充主/详细结构.显然,当我嵌套结果集时,我得到一个BAD Access异常:

FMDatabase *db = self.database;
[db open];
db.traceExecution = YES;
db.logsErrors = YES;
FMResultSet *rs = [db executeQuery:@"select group_id, label from main.preference_group order by group_id"];
while ([rs next])
{
    PreferenceGroup *pg = [[PreferenceGroup alloc] init];
    pg.group_id = [rs intForColumn:@"group_id"];
    pg.label = [rs stringForColumn:@"label"];
    pg.translatedLabel = NSLocalizedString(pg.label, nil);
    NSMutableArray * prefs = [[NSMutableArray alloc] init];
    [prefGroups addObject:prefs];
    FMResultSet *rs2 = [db executeQuery:@"select pref_id, label, value from main.preference where group_id = ? order by pref_id", pg.group_id, nil];
        while ([rs2 next])
        {
            Preference * pref = [[Preference alloc] init];
            pref.group_id = pg.group_id;
            pref.pref_id = [rs2 intForColumn:@"pref_id"];
            pref.label = [rs2 stringForColumn:@"label"];
            pref.value = [rs2 stringForColumn:@"value"];
            pref.translatedLabel = NSLocalizedString(pref.value, nil);
            [prefs addObject:pref];
        }
        [rs2 close];
    }
    [rs close];
    [db close];

在rs2(第二个结果集)中,我在FMDatabase类中获得了EXEC_BAD_ACCESS.

这是sqlite3/fmdb的限制还是我在这里做错了什么？

Answer 1

我刚刚发现我做错了什么。我传递了一个 int 作为第二个查询的一部分。我必须将其转换为 NSNumber：

            FMResultSet *rs2 = [db executeQuery:@"select pref_id, label, value from main.preference where group_id = ? order by pref_id", [NSNumber numberWithInt:pg.group_id], nil];

这意味着，是的，sqlite3/fmdb 确实支持嵌套查询！:-)