Any recommendations to improve this function?
<p>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).</p>

<pre><code>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]) &gt; 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)
</code></pre>

<hr>

<p>after following the advices, this is what I got:</p>

<pre><code>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) &gt; 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)
</code></pre>
