问题
I have a magic number in the following code...
Microsoft.Practices.EnterpriseLibrary.Data.Database db = /* code omitted */;
db.AddOutParameter(command, "@ParamName", DbType.Int32, 8);
Is there a clean way to get the length of DbType.Int32, as required for the last argument to AddOutParameter?
回答1:
Not sure what you mean about length. It's a 32 bit int so it's 4 bytes which can be 10 digits as described in this quote from this MSDN page. An integral type representing signed 32-bit integers with values between -2147483648 and 2147483647.
I'm not sure hat specifying the size (the 8) for an int32 makes sense. For example, if it should map to an Oracle Number with a specified size of 8 it should probably be DbType.Decimal rather than Int32.
I'd suggest looking into just removing the 8 altogether since it's an output parameter I don't think it would affect anything.
来源：https://stackoverflow.com/questions/3108881/addoutparameter-non-magic-number-way-of-finding-length-of-dbtype-int32