在Python中将数据从MySQL导出到CSV

Question

import mysql.connector

sql = "SELECT r.sensorID, s.area, r.date, r.Time, r.waterLevel, r.redalert FROM sensor s INNER JOIN rainfall r ON s.sensorID = r.sensorID ORDER BY r.date, Time INTO OUTFILE 'C:/ProgramData/MySQL/MySQL Server 8.0/Uploads/rainDB.csv' FIELDS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '"' LINES TERMINATED BY '\n';"

mycursor.execute(sql)

我想在我的 Python IDE 中执行上面的代码，将数据导出到一个 CSV 文件中。 select 语句在 MySQL 工作台中运行良好。 但是，当我在 Pycharm 中尝试时，我不断收到以下错误：

File "C:/Users/user/PycharmProjects/pythonProject1/BIrainSensor.py", line 106
    sql = "SELECT r.sensorID, s.area, r.date, r.Time, r.waterLevel, r.redalert FROM sensor s INNER JOIN rainfall r ON s.sensorID = r.sensorID ORDER BY r.date, Time INTO OUTFILE 'C:/ProgramData/MySQL/MySQL Server 8.0/Uploads/rainDB.csv' FIELDS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '"' LINES TERMINATED BY '\n';"
                                                                                                                                                                                                                                                                                                                         ^
SyntaxError: unexpected character after line continuation character

我认为这是由于引号内的反斜杠 n (\n)。 有没有办法解决这个问题，或者我应该找到另一种方法将数据导出到 CSV 文件中。

Answer 1

您需要添加\ （反斜杠）以转义" （因为您使用它来定义查询字符串）和\字符。

请参考 Python String and Bytes literals https://docs.python.org/3/reference/lexical_analysis.html#string-and-bytes-literals

例子：

sql = "SELECT r.sensorID, s.area, r.date, r.Time, r.waterLevel, r.redalert FROM sensor s INNER JOIN rainfall r ON s.sensorID = r.sensorID ORDER BY r.date, Time INTO OUTFILE 'C:/ProgramData/MySQL/MySQL Server 8.0/Uploads/rainDB.csv' FIELDS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '\"' LINES TERMINATED BY '\\n'"

或者更好的是，您可以使用带前缀字母“r”的三引号字符串将其标记为原始字符串。 这样你就可以避免 escaping 个字符：

sql = r"""SELECT r.sensorID, s.area, r.date, r.Time, r.waterLevel, r.redalert
FROM sensor s
INNER JOIN rainfall r ON s.sensorID = r.sensorID
ORDER BY r.date, Time
INTO OUTFILE 'C:/ProgramData/MySQL/MySQL Server 8.0/Uploads/rainDB.csv'
FIELDS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '"' LINES TERMINATED BY '\n'
"""