On 10/9/11 11:15 AM, Steve Teale wrote:
If using variants for a set of out parameters you must have something
equivalent to:
Variant[3] va;
va[0] = cast(byte) 0;
va[1] = 0.0F;
va[2] = cast(char[]) [];
So you have to have exactly the same information at compile time for the
Variant array as you do for the struct - you still have to specify a set
of types.
Not at all, fortunately it's much simpler than that. Far as I can tell,
a resultset emitted by a DBMS comes in the form of data (either untyped
buffers or strings) plus column type information, usually in the form of
an enumeration (e.g. 0 for NULL, 1 for int, 2 for double, 3 for string
etc). You of course also have the total column count. So all you need to
do is use that enum to pour the data into the Variants.
See this for example:
http://msdn.microsoft.com/en-us/library/ms131297.aspx
You can glean all needed information from the resultset after having
issued the query.
It's probably true to say that the syntax/semantics of the interface will
suck slightly more in the Variant case than in the struct case.
That's a given. The suckiness won't come, however, in the form of
additional trips to the database.
Andrei
