sql server - Incorrect value being passed in to SQL from .NET sqlcommand -

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why when run below code, should insert value of 122387593.6 table, insert value of 122387593.59999999?

i have traced call made .net , can see value being passed in 122387593.59999999 sql, yet while debugging parameter value returned 122387593.6?!

i have not been able work out why .net doing - appreciated.

   ---sql code     create table [dbo].[tblnum]( [num] [numeric](28, 8) not null    ) on [primary]      create procedure spnuminsert (@num numeric(28,8))       begin    insert tblnum values(@num)    end    go     --.net code      dim = double.parse("122387593.6", globalization.cultureinfo.invariantculture)      dim con sqlconnection = new sqlconnection("server=server;database=database;trusted_connection=true;")     dim com sqlcommand = new sqlcommand("spnuminsert", con)     com.commandtype = commandtype.storedprocedure     com.parameters.add(new sqlparameter("@num", a))      con.open()     com.executenonquery()     con.close()     con.dispose()

double means ieee754. ieee754 cannot express every single value. quite possible 122387593.6 does not exist in ieee754, , 122387593.59999999 nearest approximation.

if need values match meat-headed humans tend agree on "exact" approximation (note contradiction in terms), should using decimal, not double.

to clear: both decimal , double forced approximate - there can fit such range of possible values finite bytes. way approximate different. decimal appropriate discrete measurements money; double appropriate continuous measurements.


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