Question

我使用For循环为三个变量distance，cty，ctry赋值。然后我想将值存储在sqlite3的表中。不幸的是，程序只在sqlite3数据库中存储For循环的第一行值：

14004   GOROKA  PAPUA NEW GUINEA

代码：

from math import sin, cos, sqrt, atan2, radians
import sqlite3

R = 6373.0

conn = sqlite3.connect('global_airports_sqlite.db')
cur = conn.cursor()
cur.execute('DROP TABLE IF EXISTS Ports')
cur.execute('''
CREATE TABLE Ports ( Delta INTEGER, City TEXT, Country TEXT )''')
coords= 'SELECT lat_decimal, lon_decimal, city, country FROM airports ORDER   
BY id ASC LIMIT 10'
for cord in cur.execute(coords):
 lat2 = radians(cord[0])
 lon2 = radians(cord[1])
 cty = cord[2]
 ctry = cord[3]
 dlon = lon2 - lon1
 dlat = lat2 - lat1
 a = sin(dlat / 2)**2 + cos(lat1) * cos(lat2) * sin(dlon / 2)**2
 c = 2 * atan2(sqrt(a), sqrt(1 - a))
 distance = int(R * c)
 cur.execute('INSERT INTO Ports (Delta, City, Country) VALUES (?,?,?)',
 (distance, cty, ctry))
 conn.commit()

如何将所有10个值存储在我的三列中：Delta，City，Country？

Answer 1

我不确定sqlite3包裹，我亲自使用pymysql;但是，我认为流程应该是一样的;

因此，我认为在开始for循环之前，您可能需要先获取数据吗？

...
cur.execute('DROP TABLE IF EXISTS Ports')
cur.execute('''
CREATE TABLE Ports ( Delta INTEGER, City TEXT, Country TEXT )''')
coords= 'SELECT lat_decimal, lon_decimal, city, country FROM airports ORDER BY id ASC LIMIT 10')
cur.execute(coords)
data = cur.fetchall()
for records in data:
  ...

试一试

Answer 2

您需要使用两个不同的游标，一个用于SELECT查询，另一个用于INSERT。当您执行第一个INSERT查询时，游标不再保留SELECT查询的剩余结果，因此循环结束。

from math import sin, cos, sqrt, atan2, radians
import sqlite3

R = 6373.0

conn = sqlite3.connect('global_airports_sqlite.db')
cur = conn.cursor()
cur2 = conn.cursor()
cur.execute('DROP TABLE IF EXISTS Ports')
cur.execute('''
CREATE TABLE Ports ( Delta INTEGER, City TEXT, Country TEXT )''')
coords= 'SELECT lat_decimal, lon_decimal, city, country FROM airports ORDER   
BY id ASC LIMIT 10'
for cord in cur.execute(coords):
     lat2 = radians(cord[0])
     lon2 = radians(cord[1])
     cty = cord[2]
     ctry = cord[3]
     dlon = lon2 - lon1
     dlat = lat2 - lat1
     a = sin(dlat / 2)**2 + cos(lat1) * cos(lat2) * sin(dlon / 2)**2
     c = 2 * atan2(sqrt(a), sqrt(1 - a))
     distance = int(R * c)
     cur2.execute('INSERT INTO Ports (Delta, City, Country) VALUES (?,?,?)',
     (distance, cty, ctry))
     conn.commit()

在python3中使用For循环在sqlite3

2 个答案: