On 2013-06-18 07:10, upperdec...@gmail.com wrote:
> I have a set of queries that are run against various
> databases/tables. The result is all the same in that I always get
> back the same field names.
>
> I query fld1, fld2, fld3, qty, qty2 from table1
> then I loop thru the results
> if fld1 = 'a' add qty to some_total1
...
> I created a database pair that contains (table1,fld1 = 'a',add qty
> to some_total1) (table2,fld2 = 'b',qty to some_total1)
> (table3,fld3 = 'c',qty2 to
> some_total1)
Given the data-structure you have, and that it's hard-coded (rather
than able to take dynamic/dangerous user input) for the table-name,
I'd do something like this (untested)
for tablename, compare_field, compare_value, source_field in (
("table1", "fld1", "a", "qty"),
("table2", "fld2", "b", "qty"),
("table3", "fld3", "c", "qty2"),
):
# using string-building rather than escaping because
# 1) we know the tablenames are hard-coded/safe from above, and
# 2) this sort of escaping often chokes query parsers
query = "SELECT fld1, fld2, fld3, qty, qty2 from %s" % tablename
cursor.execute(query)
name_index_map = dict(
(info[0], i)
for info, i in enumerate(cursor.description)
)
for row in cursor.fetchall():
db_value = row[name_index_map[compare_field]]
if db_value == compare_value:
addend = row[name_index_map[source_field]]
some_total_1 += addend
-tkc
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