Re: [Orclib-users] installing latest OCILIB release; does OCILIB convert to Number when working with BINARY_DOUBLE?

[vincent r. <vin...@ya...>]

Hi,

1=> it is better to uninstall previous version and make a clean new install

2=> when using double C datatype in binding operation, the double host
variable or array is directly passed to oracle. Bu you don't know how the
oracle performs the values assigment. Regarding the documentation it seems
to be a direct assignment.

Regards

Vincent
Le 25 août 2012 16:18, <mod...@co...> a écrit :

> Hello, I have two OCILIB questions.
>
> 1) I installed OCILIB last year and have been happily using it. Now I see
> there is a new release with some features I'd like to use. If I wish to
> install the latest release, what is the procedure? That is, do I need to
> un-install anything? Or, do I simply follow the original installation
> instructions again, as documented in the OCILIB User Guide (and OCILIB with
> take care of itself)?
>
> 2) I don't see mention of BINARY_DOUBLE in the OCILIB User Guide, or
> anywhere else. Suppose I have a table in Oracle 11.2 database, with a
> column that is BINARY_DOUBLE datatype, and I use a PL/SQL stored procedure
> to select data from that column and place it, for example, in a variable
> out_data. When I retrieve out_data into the C variable myData using the
> following lines,
>
> double myData=0;
> ...
> OCI_Prepare(st, "begin get_my_data(:out_data); end;")
> OCI_BindDouble(st, ":out_data", &myData);
> OCI_Execute(st);
>
> will OCILIB convert the PL/SQL BINARY_DOUBLE variable out_data to Number
> datatype? Or, will OCILIB simply take the BINARY_DOUBLE variable out_data
> and map it exactly (via IEEE 754) into the C variable myData which is
> double datatype? I'm hoping there is a straight mapping to double so
> there's no conversion to Number that introduces conversion errors. If
> OCILIB does first convert to Number, is there a workaround?
>
> I also have this same question for OCI_BindArrayOfDoubles.
>
> I would think Oracle's Numerical Precedence would prevent conversion to
> Number, since it first looks at whether the variables involved are
> BINARY_DOUBLE and should therefore not convert to Number since out_data is
> BINARY_DOUBLE and myData is double. But I really have no idea what OCILIB
> is doing.
>
> -----------------------------------------------------------
> The following is from Oracle documentation:
>
> Numeric Precedence Numeric precedence determines, for operations that
> support numeric datatypes, the datatype Oracle uses if the arguments to the
> operation have different datatypes. BINARY_DOUBLE has the highest numeric
> precedence, followed by BINARY_FLOAT, and finally by NUMBER. Therefore, in
> any operation on multiple numeric values:
>
> •If any of the operands is BINARY_DOUBLE, then Oracle attempts to convert
> all the operands implicitly to BINARY_DOUBLE before performing the
> operation.
>
> •If none of the operands is BINARY_DOUBLE but any of the operands is
> BINARY_FLOAT, then Oracle attempts to convert all the operands implicitly
> to BINARY_FLOAT before performing the operation.
>
> •Otherwise, Oracle attempts to convert all the operands to NUMBER before
> performing the operation.
>