Problem rounding values at Post
lazarus / 16-Databases

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derles · 2014-06-03 20:36

Hello.
I have this problem:

My database (Firebird) has a table with the following fields:
...
rTitle DECIMAL(8,4) not null,
rDiameter DECIMAL(10,6) not null,
...

In my program I have a Form with a a TZTable object (ZEOS) called
zData, bound to that table.
In a routine I have the following code:

Code: [Select]zData.Insert;
...
zData.FieldByName('rTitle').AsFloat := 0.12;
zData.FieldByName('rDiameter').AsFloat := 0.12;
...
zData.Post;


Then, at the table, I see that the values ​​are stored as follows:

rTitle = 0.1199
rDiameter = 0.12

Do not know why rTitle is 0.1199 instead of 0.12
I need the saved values ​​are accurate.
I've tried AsFloat, AsCurrency, Value, always with the same result.

Any idea?

Tks.
Daniel.

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derles · 2014-06-03 21:35

Strange. I tried many values and y found this happens:

...
inserting 0.06 stored as 0.0599
0.07 --> 0.07
0.08 --> 0.08
0.09 --> 0.0899
0.10 --> 0.10
0.11 --> 0.11
0.12 --> 0.1199
0.13 --> 0.13
0.14 --> 0.14
0.15 --> 0.1499
0.16 --> 0.16
0.17 --> 0.17
0.18 --> 0.1799
...

could be a bug ?

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mangakissa · 2014-06-04 09:10

It depends.
I don't  have ZEOS and test it with SQLDB. Used two databases: MySQL
and Firebird.
First I inserted a record outside Lazarus. Thats seems to be okay.
Than created a small example in Lazarus and inserted in both
databases.
All these results were the same.

So it could be a problem in ZEOS. Does you application give you the
wrong values from the table after inserting?

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derles · 2014-06-04 11:06

I read the table from my application and from FlameRobin. Wrong values
in both cases.

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miab3 · 2014-06-04 11:59

@derles,

For ZEOS 7.2 (R3130):
http://svn.code.sf.net/p/zeoslib/code-0/branches/testing-7.2/
This effect is not observed.

Lazarus 32/64(fpc 2.7.1) on Windows7-64(CodeTyphon ver 4.80), Firebird
2.5.3.

Michal

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marcov · 2014-06-04 18:26

See if /firebird/ has a currency type. Probably DECIMAL is floating
point, and not all numbers and common fractions can be exactly
represented in floating point.

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BigChimp · 2014-06-04 18:46

See the thread on the mailing list for a post about what Firebird
decimal is in dialect 1 and 3...