I am very new to working with SQL queries. Any suggestions to improve this bit of code:
(by the way, I really don’t care about sql security here; this is a bit of code that will be in a pyexe file connecting to a local sqlite file – so it doesnt make sense to worry about security of the query here).
def InitBars(QA = "GDP1POP1_20091224_gdp", QB = "1 pork", reset = False):
global heights, values
D, heights, values, max, = [], {}, {}, 0.0001
if reset: GHolder.remove()
Q = "SELECT wbcode, Year, "+QA+" FROM DB WHERE commodity='"+QB+"' and "+QA+" IS NOT 'NULL'"
for i in cursor.execute(Q):
D.append((str(i[0]) + str(i[1]), float(i[2])))
if float(i[2]) > max: max = float(i[2])
for (i, n) in D: heights[i] = 5.0 / max * n; values[i] = n
Gui["YRBox_Slider"].set(0.0)
Gui["YRBox_Speed"].set(0.0)
after following the advices, this is what I got:
def InitBars(QA = "GDP1POP1_20091224_gdp", QB = "1 pork", reset = False):
global heights, values; D, heights, values, max, = [], {}, {}, 0.0001
if reset: GHolder.remove()
Q = "SELECT wbcode||Year, %s FROM DB WHERE commodity='%s' and %s IS NOT 'NULL'" % (QA, QB, QA)
for a, b in cursor.execute(Q):
if float(b) > max: max = float(b)
values[a] = float(b)
for i in values: heights[i] = 5.0 / max * values[i]
Gui["YRBox_Slider"].set(0.0); Gui["YRBox_Speed"].set(0.0)
If this is a one-off script where you totally trust all of the input data and you just need to get a job done, then fine.
If this is part of a system, and this is indicative of the kind of code in it, there are several problems:
Don’t construct SQL queries by appending strings. You said that you don’t care about security, but this is such a big problem and so easily solved, then really — you should do it right all of the time
This function seems to use and manipulate global state. Again, if this is a small one-time use script, then go for it — in systems that span just a few files, this becomes impossible to maintain.
Naming conventions — not following any consistency in capitalization
Names of things are not helpful at all. QA, D, QB, — QA and QB don’t even seem to be the same kind of thing — one is a field, and the other is a value.
All kinds of questionable things are uncommented — why is max .0001? What the heck is GHolder? What could that loop be doing at the end? Really, the code should be clearer, but if not, throw the maintainer a bone.