[Solved] Linux mdbtools-odbc longint data
lazarus / 16-Databases

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iru · 2016-04-28 11:29

Gentlefolk,

Environment: Linux Mint 17.3, Laz 1.6, fpWeb installed.
Underlying ODBC is "mdbtools" (the only ODBC mechanism system that I
could install and run without obscure installation problems, a driver
that worked, etc (I may be the problem here!)).

I have a program which successfully access an Access/jet/.mdb
database.
It will read a table and display "character" columns correctly.

"LongInt" integers do not display correctly!

The statement  "
SQLBindCol(stmtHandle,1,SQL_INTEGER,SQLPointer(@ResID),4,@ErrCode);"
defines column1 in the table.

The statement "Res:=SQLFetch(StmtHandle);" makes each entry in the
table accessible.
The contents of column 1 should be accessible in "ResID" Which is a
"LongInt".

I can inspect the contents of the .mdb file with the MDBTOOLS file
viewer and display the table and correct values for column 1 (for
example a row entry with column 1 = 752) .

Using the Bless hex editor I can inspect the contents of the .mdb file
and locate the appropriate row and  column 1. In hex it is F2:02:00:00
which is 752 in "little endian" format.

Run the program and I get ResID = 842348288, SwapEndian(ResID) =
ResDebug = 3618098 (may actually be from a row with col 1 = 751 or 753
(having problems with the row count.....))

Any help appreciated, Ian.

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marcov · 2016-04-28 11:44

Quote from: iru on April 28, 2016, 01:29:21 pm ResID = 842348288,

This is hex $32353700  which is an ascii string #0'752'

So it seems a string is interpreted as integer somewhere.

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iru · 2016-04-29 05:40

Marcov,

Well done!!!! I did not see that at all.

There is something funny down in the odbc-access API. Everything I can
see indicates that the returned data should be a LongInt.

Thanks, Ian.

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mig-31 · 2016-04-29 08:10

Why are you using mdb (Access file) database under Linux?
It is better to use SQL Lite or Firebird or other. You can a access to
SQL Lite/Firebird through ODBC driver or directly.