如何使用Python将NULL值插入PostgreSQL数据库？ [英] How to insert 'NULL' values into PostgreSQL database using Python?

问题描述

在Python中变量为 None 时，是否存在将 NULL 键值输入到PostgreSQL数据库的良好实践？ ？

Is there a good practice for entering NULL key values to a PostgreSQL database when a variable is None in Python?

运行此查询：

mycursor.execute('INSERT INTO products (user_id, city_id, product_id, quantity, price) VALUES (%i, %i, %i, %i, %f)' %(user_id, city_id, product_id, quantity, price))

在 user_id <时导致aa TypeError 异常/ code>是 None 。

results in a a TypeError exception when user_id is None.

NULL psycopg2 驱动程序将c $ c>值插入 None 插入数据库吗？

How can a NULL be inserted into the database when a value is None, using the psycopg2 driver?

推荐答案

要将空值插入数据库，您有两个选择：

To insert null values to the database you have two options:

1. 从您的INSERT语句中忽略该字段，或


2. 使用 None

1. omit that field from your INSERT statement, or
2. use None

也：为了防止SQL注入，您不应该对查询使用普通的字符串插值es。

Also: To guard against SQL-injection you should not use normal string interpolation for your queries.

您应将两（2）个参数传递给 execute（），例如：

You should pass two (2) arguments to execute(), e.g.:

mycursor.execute("""INSERT INTO products 
                    (city_id, product_id, quantity, price) 
                    VALUES (%s, %s, %s, %s)""", 
                 (city_id, product_id, quantity, price))

备用＃2：

user_id = None
mycursor.execute("""INSERT INTO products 
                    (user_id, city_id, product_id, quantity, price) 
                    VALUES (%s, %s, %s, %s, %s)""", 
                 (user_id, city_id, product_id, quantity, price))

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