Is there a maximum size to a Python program?

Duncan Booth duncan.booth at invalid.invalid
Mon Apr 27 12:05:49 CEST 2009


Lawrence D'Oliveiro <ldo at geek-central.gen.new_zealand> wrote:

> In message <gt3fv1$1aci$1 at news.ett.com.ua>, Paul Hemans wrote:
> 
>> One problem though that I didn't mention in my original
>> posting was that the replication may only require updating one or
>> more fields, that is a problem with a generating a single SQL
>> statement to cover all requests.
> 
> That's not a big issue. Assume the field names and corresponding
> values are coming from a Python dict, eg
> 
>     FieldValues = \
>       {
>         "field1" : ... value1 ...;
>         "field2" : ... value2 ...;
>      }
> 
> then you can construct an SQL statement on the fly with something like
> 
>     sqlcmd = \
>         (
>             "insert into my_table set "
>         +
>             ", ".join
>               (
>                 "%s = %s" % (k, SQLString(FieldValues[k]))
>                     for k in FieldValues.keys()
>               )
>         )
> 
> where SQLString is as defined at 
><http://codecodex.com/wiki/index.php?
title=Useful_MySQL_Routines#Quoting
>>. 
> 
> 

Not so nice if the input data is something like:

    	FieldValues = { "field1=0);DROP my_table;": "" }

So you want something to validate fieldnames.

Also you are assuming that all the values are strings: if you want to 
handle different data types correctly it is probably simpler to insert 
parameter placeholders in the dynamic sql statement and just pass 
FieldValues.items() to the execute method.

-- 
Duncan Booth http://kupuguy.blogspot.com



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