Cannot read a table with a byte field

[ellis2323]

I'm trying to read the table tRelais in this mdb:
https://u.pcloud.link/publink/show?code=XZu5EHVZVqot9BBBU7FMwQHIVSJ4zHIwB9i7

If I read this table with "sysinfotool MDB file viewer 20.0", I read a full table with no empty data. But, if I read with this library, I found many empty object:

{NoEngageRelais: 1487, NoEngagement: 44242, NoSerieTour: 8096, NoAthlete: 13310, NoOrdreRelais: null}
{NoEngageRelais: 1488, NoEngagement: 44242, NoSerieTour: 8096, NoAthlete: null, NoOrdreRelais: null} ...

The field NoOrdreRelais has the type octet in french language... It is a small int with 8bits.

My script:

function loadRelais (reader) {
  let cmtrelays = new Map()
  const table = reader.getTable('tRelais')
  let rows = table.getData()
  for (let row of rows) {
    console.log(row)
    let uid = row.NoEngageRelais
    let noEngagement = row.NoEngagement
    let serieTour = row.NoSerieTour
    let athUID = row.NoAthlete
    let ord = row.NoOrdreRelais
    cmtrelays.set(uid, { uid, noEngagement, serieTour, athUID, ord })
  }
  return cmtrelays
}

[andipaetzold]

👋 Hello again,

I was able to reproduce the issue. The problem seems to be that that row thinks it has more variable columns than total columns.
How was this table created? Was there a lot of altering and moving of the columns? Are you able to reproduce such broken table from scratch?

I'll hope I find time next week to investigate this further. There seems to be a related issue when only a subset of columns is read...

[ellis2323]

Hello,

This table is created by an access application developed by a french company 20 years ago and maintained until now. When you say "only a subset of columns is read", which alternative is available ?

[andipaetzold]

20 years ago and maintained until now.

Yeah, I noticed that. Can't even open the file in a current Microsoft Access :(

When you say "only a subset of columns is read", which alternative is available ?

This is probably unrelated to your problem. It might lead to the same result (null values), but when calling getData() with a columns option. I need to do more investigation around this.

I don't see any workaround at the moment.

[ellis2323]

I've a computer with XP and Access97. This table is the one with this short int of one byte. Are you sure this type of data is well read ?

[andipaetzold]

Yes, the column definitions are read correctly. If not, you would get null everywhere.

The issue is that fixedColumnCount becomes a negative number (

mdb-reader/src/Table.ts

Line 318 in a9847d6

const fixedColumnCount = totalVariableCount - variableColumnCount;

) because variableColumnCount is greater than totalVariableCount. If that happens, we end up in the else branch (

mdb-reader/src/Table.ts

Lines 350 to 352 in a9847d6

	start = 0;
	value = null;
	size = 0;

) when reading the row and the value becomes null.

[ellis2323]

Hello,

When i read this table, I miss 1 column (NoOrdreRelais) for the first row, then I miss two columns (NoAthlete, NoOrdreRelais), then 3 columns (NoSerieTour, NoAthlete, NoOrdreRelais), then 4 columns and then it loop again with one column missing, then two.... The written values are correct.

relais {
NoEngageRelais: 228,
NoEngagement: 1222,
NoSerieTour: 444,
NoAthlete: 666,
NoOrdreRelais: null
}
relais {
NoEngageRelais: 229,
NoEngagement: 1222,
NoSerieTour: 444,
NoAthlete: null,
NoOrdreRelais: null
}
relais {
NoEngageRelais: 230,
NoEngagement: 1222,
NoSerieTour: null,
NoAthlete: null,
NoOrdreRelais: null
}
relais {
NoEngageRelais: 231,
NoEngagement: null,
NoSerieTour: null,
NoAthlete: null,
NoOrdreRelais: null
}

[ellis2323]

The table in Access97 have 5 fields:

• NoEngageRelais: AutoNumber
• NoEngagement: Numeric
• NoSerieTour: Numeric
• NoAthlete: Numeric
• NoOrdreRelais: Numeric

All columns are defined and set.

[ellis2323]

I have installed mdb-tools in a VM and I can read the data:

mdb-export /mnt/c/Users/laure/Downloads/nxtcrsu.nxt tRelais
NoEngageRelais,NoEngagement,NoSerieTour,NoAthlete,NoOrdreRelais
228,1222,444,666,1
229,1222,444,791,2
230,1222,444,639,3
231,1222,444,612,4
232,1223,445,782,1
233,1223,445,780,2
234,1223,445,752,3
235,1223,445,795,4
236,1226,444,624,1
237,1226,444,609,2
238,1226,444,634,3
239,1226,444,626,4
240,1226,476,624,1
241,1226,476,609,2
242,1226,476,634,3
243,1226,476,626,4
244,1222,476,666,1
245,1222,476,791,2
246,1222,476,639,3
247,1222,476,612,4
248,1223,477,782,1
249,1223,477,780,2
250,1223,477,752,3
251,1223,477,795,4

[andipaetzold]

I think I found the issue. Seems like this was just a small mistake in the Jet3 format configuration.
The new version should release any minute. Please let me know if you still run into issues with the latest update.

[ellis2323]

Hello,

I tried this morning and everything is ok. Good job.

Thanks for your great work.