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中执行以上代码，以将数据导出到CSV文件。 select语句在MySQL工作台中工作正常。但是，当我在Pycharm中尝试时，仍然出现以下错误：

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）。有没有解决此问题的方法，还是我应该寻找另一种方法将数据导出到CSV文件。

Answer 1

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

请参考Python字符串和字节文字https://docs.python.org/3/reference/lexical_analysis.html#string-and-bytes-literals

示例：

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'"

甚至更好的是，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。这样可以避免转义字符：

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'
"""

在Python中将数据从MySQL导出到CSV

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