Python:将数据从大型csv导入sqlite DB

时间:2017-05-28 03:57:39

标签: python mysql sqlite csv

我正在尝试使用python脚本将数据从csv文件导入到sqlite数据库。

我的CSV行如下:(在从quandle下载的excel表中)

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

为了创建数据库表,我使用了以下脚本:

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()

对于在表的特定行中插入数据,我使用以下脚本,但是由于浮点转换给出错误,数据插入失败,任何指导都将非常受欢迎。

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()

1 个答案:

答案 0 :(得分:0)

csv示例与代码不匹配 - 在后者中你跳过一行(可能是标题),其中第一个单元格是' DATE' - 并且在csv中它是' Date'。

考虑使用csv.DictReader - 它会为每个源行生成一个dict,其中一列是一个键:

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 - 不要手动解析原始csv,而是使用内置库 - 这样可以省去很多麻烦。

例如,您尝试处理空行,跳过标题行;但在csv中还有其他一些例子 - 例如数据引用和转义,库将为你处理。