Wrong subquery
See original GitHub issueI’m using Linq2Db v5.2.2 in a .NET7.0 project. I have this code
await using var db = new Database.Database();
var pcScanHdd = GetPcScanId(db, ScanFlags.HardDisks);
//var a = await pcScanHdd.ToListAsync();
var query =
from ps in pcScanHdd
join pc in db.Pcs on ps.PcId equals pc.Id
join scan in db.Scan on ps.ScanId equals scan.Id
join disk in db.LogicalHdds on scan.Id equals disk.ParentId
where disk.MediaType == MediaTypeEnum.FixedHardDisk
&& disk.DriveType == DriveTypeEnum.LocalDisk
select new { pc, scan, disk };
GetPcScanId
is a function returning an IQueryable<PcScanId>
where PcScanId is defined as
private record PcScanId
{
public int PcId;
public int ScanId;
}
var pcScanHdd = GetPcScanId(db, ScanFlags.HardDisks)
returns this query
SELECT
pc.id,
Max(scan_1.id)
FROM
scan scan_1
INNER JOIN pcs pc ON scan_1.id_parent = pc.id
WHERE
pc.endDate IS NULL AND @flags = (scan_1.flags & @flags_1)
GROUP BY
pc.id
If I try var a = await pcScanHdd.ToListAsync();
I get correct result.
Unfortunately when I use pcScanHdd in the next query, subquery is completely wrong:
FROM
(
SELECT
0 as PcId
FROM
scan scan_1
INNER JOIN pcs pc ON scan_1.id_parent = pc.id
WHERE
pc.endDate IS NULL AND @flags = (scan_1.flags & @flags_1)
GROUP BY
pc.id
) ps
INNER JOIN pcs pc_1 ON ps.PcId = pc_1.id
INNER JOIN scan scan_2 ON ps.PcId = scan_2.id
INNER JOIN info_logicaldisk disk ON scan_2.id = disk.id_parent
WHERE
disk.MediaType = 12 AND disk.DriveType = 3
SELECT 0 as PcId
is bad, but INNER JOIN scan scan_2 ON ps.PcId = scan_2.id
is a nonsense.
I can’t understand why it works if I execute the query itself, but it goes bad when I use it in another query.
Issue Analytics
- State:
- Created 3 months ago
- Comments:14 (7 by maintainers)
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Well it is doable in different way:
Seems like with your updated query it’s working. Let me test it some more… and thank you 😃