FreeTDS Development Group

[ZIGLIO Frediano <Frediano.Ziglio AT vodafoneomnitel.it>]

> 
> > ODBC (I don't know other api) have a function to return 
> parameter type
> > for dynamic query. This function is quite easy to implement 
> on Sybase
> > (Sybase return all parameter type) while hard on mssql, requiring
> > parsing of query and get manually type of pararameters, see at 
> > 
> http://msdn.microsoft.com/library/default.asp?url=/library/en-
>  us/odbcsql/od_odbc_d_1not.asp
> 
> From the [limited] point of view of DBD::ODBC, parameter
> description is not strictly necessary.  All is really needed
> is to retrieve the parameter types from the bound variables,
> which means that you have to actually prepare the statement
> not at the SQLPrepare call, but at the first SQLExecute.
> 

Correct, same behaviour of ms odbc

> This is what I understand (by packet sniffing) the MS SQL Server
> 'official' driver is doing.
> 
> Moreover, using the MS driver, if you do not explicitly
> bind variables with a type in a DBD::ODBC statement,
> [using bind_param], the default type is used, which is,
> apparently, varchar(80).  
> 

How can I bind a parameter without type ??

> What I am trying to say is that if we limit ourselves to DBD:ODBC
> "compliance", there are relatively little problems.
> 

Many people use ODBC with DBD::ODBC, so seem a good test. But I think
finally to provide a fill ODBC implementation...

> If, on the other hand,
> we want to fully implement SQLDescribeParam, we have to completely
> parse the SQL statement, or to accept some limitation on the syntax
> which is handled.  In the first hypotesis, I would like to
> use an existing SQL parser, because I'm afraid that writing one
> from scratch is unreasonable.  In the latter hypotesis,
> a consensus must be reached on what the limitations are.
> 

If I try to exec SQLDesbribeParam on "create table #test(a int, b
varchar(10)) insert into #test(a,b) values(?,?)" it return "invalid columns
number" (??? strange error...). When I exec SQLDesbribeParam on "insert into
#test(a,b) values(?,?)" it return right information..

I think first point it to change tds_dynamic_* function for supporting
TDS7/8 (and perhaps 4.2 but do not seem so useful) using RPC, then rebuild
ODBC prepare stuff using dynamic query...

freddy77

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