mysql/python 连接器在处理空值时使用参数和字典死机

Posted 2023-03-16

【中文标题】mysql/python 连接器在处理空值时使用参数和字典死机

【英文标题】：mysql/python connector using a params and a dictionary dying when handling a null value

【发布时间】：2014-06-12 08:42:19

【问题描述】：

insert_statement = ("INSERT INTO mydb.sets_ledger "
    "( exercise, weight, reps, rpe) "
    "VALUES ( %(Exercise)s, %(weight)s, %(reps)s, %(rpe)s")

#import the CSV file
workout_file = "squat_rpe.csv"
file_hook = open(workout_file, 'rb')
dictionary=csv.DictReader(file_hook)

print dictionary.dialect
print dictionary.fieldnames

for row in dictionary:
    print row['Day'], row['Exercise'], row['weight'], row['reps'], row['rpe']
    print "==> "
    cursor.execute(insert_statement, row)

当我从字典中的其中一列（在本例中为“rpe”列为空的情况下）输入一行时，它崩溃了。

row =    'rpe': '', 'weight': '60', 'reps': '3', 'Day': '04/26/14', 'Exercise': 'Competition Back Squat’

给我最后的错误

mysql.connector.errors.ProgrammingError: 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 1

rpe、reps、weight 的 mysql 架构都是小数(10,5)

当数据周围有空值时，如何使用字典/参数方法生成 sql 查询？

====================================

我建立了一个单独的测试：

import csv
import mysql.connector

#engage the MySql Table
cnx= mysql.connector.connect(user='root', host='127.0.0.1', database='mydb')
cursor = cnx.cursor()


insert_statement_dic = ("INSERT INTO mydb.sets_ledger "
    "( exercise, rpe) "
    "VALUES ( %(exercise)s, %(rpe)s)")

insert_statement_tuple = ("INSERT INTO mydb.sets_ledger "
    "( exercise, rpe) "
    "VALUES ( %s, %s)")

tuple_param_10 = ('tuple insert test 10', 10)
tuple_param_pure_none = ('tuple insert test None', None)
tuple_param_quoted_none = ('tuple insert test quoted none', 'None')

cursor.execute(insert_statement_tuple, tuple_param_10);
cursor.execute(insert_statement_tuple, tuple_param_pure_none);
#cursor.execute(insert_statement_tuple, tuple_param_quoted_none);

dic_param_10 = 'exercise': 'dic_param_10', 'rpe': 19
dic_param_None = 'exercise': 'dic_param_None', 'rpe': None
dic_param_quoted = 'exercise': 'dic_param_None', 'rpe': 'None'

cursor.execute(insert_statement_dic, dic_param_10);
cursor.execute(insert_statement_dic, dic_param_None);
#cursor.execute(insert_statement_dic, dic_param_quoted);


cnx.commit()
cursor.close()
cnx.close()

要在十进制列中插入“无值”（NULL），我需要插入 >None'''None'

这意味着当我从逗号分隔值构建参数字典时，我需要执行一个清理函数，将任何空字符串 ('') 转换为 _builtin.None。 （除非我能想出办法让 CSV 模块自动将空字符串 ('') 转换为 None。

【参考方案1】：

错误不是关于您的值是空的，而是关于您的查询中的错误。错误消息只是提示您在查询中发生解析错误的位置，即''。

如果您在查询后打印cursor._executed，您会看得更清楚，它应该会显示如下内容：

INSERT INTO ... VALUES ( ..., ''

如您所见，真正的问题是您的查询缺少右括号，它应该是：

insert_statement = ("INSERT INTO mydb.sets_ledger "
     "( exercise, weight, reps, rpe) "
     "VALUES ( %(Exercise)s, %(weight)s, %(reps)s, %(rpe)s )")

【讨论】：

_executed = 'INSERT INTO mydb.sets_ledger ( exercise, weight, reps, rpe) VALUES ( \\'Competition Back Squat\\', \\'60\\', \\'3\\', \\'\\’)' 如果我删除了“\”并将该查询直接输入 mysql，它会抱怨我将 '' 插入 rpe（这是一个小数（10,5））Error Code: 1366. Incorrect decimal value: '' for column 'rpe' at row 1