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Looking for C & SQL parm tips/experiences.

From: Dave Egan - N6XVZ <daveegan_at_dhw68k.cts.com>
Date: Thu, 11 Feb 1993 00:32:06 GMT
Message-ID: <1993Feb11.003206.9136_at_dhw68k.cts.com> 







We are designing a system that will be written in C and 
accesses a relational database (using embedded SQL or possibly
a popular RDBMS API).  This a a very large application that will 
involve hundreds of modules and approximately 36 tables.  
The sheer size of the task complicates what can normally be 
considered a straight-forward method of passing parameters.  
We want to keep our database calls in a lower layer and have 
been kicking around alternatives for how to set up the calling 
interface.



We've come up with two different methods so far and corresponding
issues:



    
  
  1.   Call the low-level SQL routine with a pointer to a structure
    that was obtained by the caller.  Or should the called routine
    do the malloc()?  We've seen cases where the caller had the
    storage defined smaller than the SQL routine, so when the 
    low-level routine moved data into it, other storage areas
    following the row definition were corrupted (makes for a
    debugging nightmare!)  Yet, if the called SQL routine gets 
    the storage, how can you guarantee that the caller gets to
    or remembers to free it later?

  
  2.   Code our SQL statements to return only the columns that are 
    needed -- everyone says that is more efficient than returning
    a whole row.  The issue here is that with hundreds of SQL
    functions, we'll have #include's for every one -- a 
    maintenance nightmare.  We could pass a single structure 
    that represents the whole row and just "fill in" the columns 
    we need, but when the row changes, all the affected programs 
    need to be recompiled.

    





So what have you folks done?  Any slick ideas?  Any experiences 
and suggestions would be greatly appreciated.



If there is sufficient interest, I'll post a response back to 
the net.


-- 
Dave Egan                                        | Radio: N6XVZ
    uucp: ...{spsd,zardoz,felix}!dhw68k!daveegan | n6xvz.ampr.org[44.10.0.176] 
        : daveegan_at_dhw68k.cts.com                | n6xvz_at_wa6fwi.#SOCAL.CA.USA.NA


Received on Thu Feb 11 1993 - 01:32:06 CET












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