Обсуждение: DescribParam
When I call SQLDescribeParam using PostgreSQL ODBC Driver psqlodbc-08_02_0002 SQL_ERROR is the return code. What I am trying to do with this call is determine the buffer size needed to allocate a buffer so I can call SQLBindParameter with a big enough buffer. I have tried defaulting this to a number > 255, but this causes some other drivers, like MS Access to choke. MS SQL Server and others return the correct parameter size. My only thought was to provide an override for this in my library to force the parameter size when the driver does not return it. Does anyone have a better workaround for this? Glenn Lawler www.incodesystems.com
> When I call SQLDescribeParam using PostgreSQL ODBC Driver > psqlodbc-08_02_0002 SQL_ERROR is the return code. This API has never been supported. Why do you use it when psqlODBC returns info that it doesn't support SQLDescribeParam? > What I am trying to do with this call is determine the buffer size > needed to allocate a buffer so I can call SQLBindParameter with > a big enough buffer. There is the problem that PgSQL backend doesn't support it before execution (I haven't found another information yet). > My only thought was to provide an override for this in my library > to force the parameter size when the driver does not return it. Maybe you may depend on other information like PostgreSQL driver, ... > Does anyone have a better workaround for this? Sorry, I don't have one. Regards, Luf
Luf, So, if SQLDescribeParam is not supported, how do you know how big to make the buffers? I assume everyone must either use a standard size for all parameters or the caller must know the right size to use. I guess I'll have to add an optional call to my library to override the buffer size after the statement has been prepared. Glenn Lawler www.incodesystems.com -----Original Message----- From: Ludek Finstrle [SMTP:luf@pzkagis.cz] Sent: Wednesday, June 07, 2006 2:24 PM To: Glenn B. Lawler Cc: 'PostgreSQL ODBC List' Subject: Re: [ODBC] DescribParam > When I call SQLDescribeParam using PostgreSQL ODBC Driver > psqlodbc-08_02_0002 SQL_ERROR is the return code. This API has never been supported. Why do you use it when psqlODBC returns info that it doesn't support SQLDescribeParam? > What I am trying to do with this call is determine the buffer size > needed to allocate a buffer so I can call SQLBindParameter with > a big enough buffer. There is the problem that PgSQL backend doesn't support it before execution (I haven't found another information yet). > My only thought was to provide an override for this in my library > to force the parameter size when the driver does not return it. Maybe you may depend on other information like PostgreSQL driver, ... > Does anyone have a better workaround for this? Sorry, I don't have one. Regards, Luf
> So, if SQLDescribeParam is not supported, how do you > know how big to make the buffers? I don't know. I'm sorry. If you find the way with PgSQL backend we'll be glad. > I assume everyone must either use a standard size for > all parameters or the caller must know the right size to > use. Or you have to know what you ask for. Please try standard size and hope that it's enough. I don't have better advice. Maybe I'm wrong and someone more experienced correct it. BTW this is comment from psqlODBC: /* * Returns the description of a parameter marker. * This function is listed as not being supported by SQLGetFunctions() because it is * used to describe "parameter markers" (not bound parameters), in which case, * the dbms should return info on the markers. Since Postgres doesn't support that, * it is best to say this function is not supported and let the application assume a * data type (most likely varchar). */ Regards, Luf
Glenn B. Lawler wrote: > When I call SQLDescribeParam using PostgreSQL ODBC Driver psqlodbc-08_02_0002 > SQL_ERROR is the return code. Are you checking the 7.4+ Protocol option ? regards, Hiroshi Inoue
Yes. -----Original Message----- From: Hiroshi Inoue [SMTP:inoue@tpf.co.jp] Sent: Wednesday, June 07, 2006 6:22 PM To: Glenn B. Lawler Cc: 'PostgreSQL ODBC List' Subject: Re: [ODBC] DescribParam Glenn B. Lawler wrote: > When I call SQLDescribeParam using PostgreSQL ODBC Driver psqlodbc-08_02_0002 > SQL_ERROR is the return code. Are you checking the 7.4+ Protocol option ? regards, Hiroshi Inoue
Glenn B. Lawler wrote: > Yes. > Isn't the error message "Invalid parameter number for PGAPI_DescribeParam." ? If so, could you call SQLNumParams before calling SQLDescribeParam on trial ? regards, Hiroshi Inoue