Python:将数据从大型csv导入到sqlite数据库
我在尝试使用python脚本将数据从csv文件导入到sqlite数据库。Python:将数据从大型csv导入到sqlite数据库
我的CSV行如下:(在从quandle下载的excel工作表)
Date Open High Low Last Close TotTrQt Turnover (Lacs)
2017-05-26 2625 2626.85 2564.65 2570.05 2578.25 681275 17665.43
2017-05-25 2577 2637.55 2568 2615.05 2624.6 2047047 53333.77
2017-05-24 2534.8 2570 2529.65 2567.1 2559.15 1267274 32252.28
2017-05-23 2533.2 2564.15 2514 2523.7 2521.7 1374298 34776.45
2017-05-22 2510 2553.75 2510 2535 2531.35 831970 21054.61
2017-05-19 2536.2 2540.55 2486 2503.85 2507.15 893022 22384.3
2017-05-18 2450 2572 2442.25 2525 2536.2 2569297 64894.78
2017-05-17 2433.5 2460.75 2423 2450 2455.35 1438099 35137.29
2017-05-16 2380 2435 2373.45 2425.1 2429.15 1800513 43397.03
2017-05-15 2375.1 2377.95 2341.6 2368 2365.1 908802 21380.43
为了产生DB表,我已经使用下面的脚本:
import sqlite3
try:
db = sqlite3.connect('NSETCS')
cursor=db.cursor()
print 'Executing: Create Table SQL'
cursor.execute('''CREATE TABLE NSETCS (DATE TEXT, OPEN REAL, HIGH REAL, LOW REAL, LAST REAL, CLOSE REAL,\
TOTALTRADEQUANTITY REAL, TURNOVER REAL)''')
##since above statment is DDL, no explicit commit is reqd
except Exception as E:
print "Error=",E
finally:
db.close()
用于插入数据在表格的特定行中,我使用下面的脚本,但是由于浮点转换给出错误,所以数据插入失败,任何指导都将非常值得赞赏。
import sqlite3
try:
infile = open (r'F:\mypractise_python\day11\NSE-TCS.csv','r')
content = infile.readlines()
except IOError as E:
print "Error: ", E
try:
db = sqlite3.connect('NSETCS')
cursor = db.cursor()
for line in content:
line =line.strip()
columns = line.split(',')
if line == '' or columns[0] == 'Date':
continue
date = columns[0].strip()
open_stock = float(columns[1].strip())
high = float(columns[2].strip())
low = float(columns[3].strip())
last= float(columns[4].strip())
close= float(columns[5].strip())
tot_trade_qt= float(columns[6].strip())
turnover= float(columns[7].strip())
cursor.execute('''insert into NSETCS values (:date, :open_stock, :high, :low, :last, :close, :tot_trade_qt, :turnover)''',\
{'date':date, 'open_stock':open_stock, 'high':high, 'low':low, 'last':last, 'close':close,\
'tot_trade_qt':tot_trade_qt, 'turnover':turnover})
except Exception as E:
print "Error:", E
else:
db.commit()
db.close()
infile.close()
该CSV样本不匹配的代码 - 在后者你跳过一排(大概是报头),其中所述第一小区是“DATE” - 和在CSV是“日期”。
考虑使用csv.DictReader - 它会为每个源行的字典,其中一列是一个关键:
import sqlite3
import csv
db = sqlite3.connect('NSETCS')
with open (r'F:\mypractise_python\day11\NSE-TCS.csv','r') as infile, db:
content = csv.DictReader(infile, delimiter=',') # csv generator to the file, will be read line by line
cursor = db.cursor()
for line in content:
# line is a dict, where each column name is the key
# no need to sanitize the header row, that was done automatically upon reading the file
date = line['Date']
open_stock = float(line['Open'])
high = float(line['High'])
low = float(line['Low'])
last= float(line['Last'])
close= float(line['Close'])
tot_trade_qt= float(line['TotTrQt'])
turnover= float(line['Turnover (Lacs)'])
cursor.execute('''insert into NSETCS values (:date, :open_stock, :high, :low, :last, :close, :tot_trade_qt, :turnover)''',\
{'date':date, 'open_stock':open_stock, 'high':high, 'low':low, 'last':last, 'close':close,\
'tot_trade_qt':tot_trade_qt, 'turnover':turnover})
# no file closing, that is automatically done by 'with open()'
# no db close or commit - the DB connection is in a context manger, that'll be done automatically (the commit - if there are no exceptions)
我的主要观点是 - 不要手工解析原始CSV,但使用内置的库 - 这将为您节省很多麻烦。
例如,您尝试处理空行,跳过标题行;但在csv中还有其他一些情况 - 数据引用和转义,例如库为您处理。
那么我的答案仍然成立 - 你试过了吗?而且,在更新后的问题代码中,即使数据样本中的列是“日期”,您也会与“DATE”(大写)合作。 – Todor
todor运行ur代码导致以下结果 错误:DictReader实例没有属性'--getitem--' –
与编辑建议,它会很好地工作。 [csv.DictReader(infile,delimiter =',')]只会代表列表和列表(csv.DictReader(infile,delimiter =','))将它转换成列表..... right? –
任何错误信息? –
给我们举例你的CSV行 –
错误:无法将字符串转换为浮动。 –