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Bug report: Patch is rounding numbers to 7 significant figures

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Posted on by Meneghino

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I use an SQL server back-end (Access Web Apps) and when Patching a number value to a number field, the number is rounded to 7 significant figures by PowerApps!!!

This is not an issue with the database since the number type is Floating-point number (variable decimal places) and it can hold many more significant figures.

Please help or give indications as this is a real issue!

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Building Power Apps

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AndyPennell Microsoft Employee on at

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Can you give a specific example of truncation? Under the hood PA uses Javascript to hold numbers, see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number for details.
AndyPennell Microsoft Employee on at

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Also "ECMA-262 only requires a precision of up to 21 significant digits"
Meneghino 6,949 on at

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Thanks @AndyPennell

21 significant digits is more than enough, but 7 is not since we cannot make the company bank accounts balance to the cent, as they should.

Here is a specific example, using an Access Web App back end;
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AndyPennell Microsoft Employee on at

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I am very rusty on T-SQL and know exactly nothing about the Access Web App back end, but from the looks of your screenshot the data is round-tripping through a SQL "float" type, and it should be using "real". (PA doesnt have an equivalent to any of the exact numeric types that SQL does).

This page indicates that a 4-byte float has a precision that exactly matches yourr experience: https://msdn.microsoft.com/en-us/library/ms173773.aspx

Unfortunately my complete lack of Access knowledge means I cannot offer a suggestion on how to "widen" the data type that is being passed on the wire. Hopefully someone else can.
Meneghino 6,949 on at

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Ok, no problem.
In any case I am only holding out unti CDS has enough functionality and Excel will have the connector to use CDS in Get&Transform (aka PowerQuery). Then I will migrate to CDS.
However, you might put a warning out there for those using Access Web Apps and similar data sources.
Meneghino 6,949 on at

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HELP! This issue is now appearing when patching an update of a number to an Azure SQL DB back end.

Here is ohw to reproduce the issue:

1) Create a table in Azure SQL DB with a money type column
2) Create a record with the value 123 in that column
3) Now patch the value 100120.99 to that column in the existing record and the database will record 100121.00 !!!

Please, please help. I am rapidly loosing all goodwill with PowerApps, and with Microsoft for forcing a quick transition from Access Web Apps to a product which is full of bugs.
Meneghino 6,949 on at

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I managed to get through to MS support, they have identified this as a bug and are working on it.