我是使用python和sqlite的新手。我正在尝试创建一个从表(Rawdata)中读取数据的脚本,然后执行一些计算,然后将其存储在一个新表中。我在计算一名球员在该日期之前在特定赛道位置赢得的比赛次数并计算出比例。共有15个轨道位置。总的来说,剧本非常缓慢。任何提高速度的建议。我已经使用了PRAGMA参数。在Sqlite中提高查询速度
以下是脚本。
for item in result:
l1 = str(item[0])
l2 = item[1]
l3 = int(item[2])
winpost = []
key = l1.split("|")
dt = l2
###Denominator--------------
cursor.execute(
"SELECT rowid FROM rawdata WHERE Track = ? AND Date< ? AND Distance = ? AND Surface =? AND OfficialFinish=1",
(key[2], dt, str(key[4]), str(key[5]),))
result_den1 = cursor.fetchall()
cursor.execute(
"SELECT rowid FROM rawdata WHERE Track = ? AND RaceSN<= ? AND Date= ? AND Distance = ? AND Surface =? AND OfficialFinish=1",
(key[2], int(key[3]), dt, str(key[4]), str(key[5]),))
result_den2 = cursor.fetchall()
totalmat = len(result_den1) + len(result_den2)
if totalmat > 0:
for i in range(1, 16):
cursor.execute(
"SELECT rowid FROM rawdata WHERE Track = ? AND Date< ? AND PolPosition = ? AND Distance = ? AND Surface =? AND OfficialFinish=1",
(key[2], dt, i, str(key[4]), str(key[5]),))
result_num1 = cursor.fetchall()
cursor.execute(
"SELECT rowid FROM rawdata WHERE Track = ? AND RaceSN<= ? AND Date= ? AND PolPosition = ? AND Distance = ? AND Surface =? AND OfficialFinish=1",
(key[2], int(key[3]), dt, i, str(key[4]), str(key[5]),))
result_num2 = cursor.fetchall()
winpost.append(len(result_num1) + len(result_num2))
winpost = [float(x)/totalmat for x in winpost]
rank = rankmin(winpost)
franks = list(rank)
franks.insert(0, int(key[3]))
franks.insert(0, dt)
franks.insert(0, l1)
table1.append(franks)
franks = []
cursor.executemany("INSERT INTO posttable VALUES (?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?)", table1)
我认为,目标应该是让SQL机器做的工作,而不是Python的一个。尝试缩小SQL查询的数量。 – karlosss