MySQL在Python中;连接在第一个循环后在for循环中关闭 [英] MySQL in Python; connection closes in for loop after first cycle

问题描述

我的MySQL连接在一个循环周期后关闭。我可能在使用mysql对象时做错了。

My MySQL connection closes after one loop cycle. I probably do something wrong in the usage of the mysql object. It outputs one cycle and then exits with an error.

这是我的代码：

cnx = mysql.connector.connect(**config)
cursor = cnx.cursor()

fetch_ids = cnx.cursor()
query = ("SELECT * FROM items WHERE has_recipe = 1")
fetch_ids.execute(query)

count = 0
for (data) in fetch_ids:
    fetch_details = cnx.cursor()
    query = ("SELECT * FROM recipes WHERE recipe_id = " + str(data[1]))
    fetch_details.execute(query)

我得到的错误是：

Traceback (most recent call last):
  File "trade.py", line 47, in <module>
    fetch_details = cnx.cursor()
  File "/Users/allendar/Desktop/mysql/connector/connection.py", line 1076, in cursor
    raise errors.OperationalError("MySQL Connection not available.")
mysql.connector.errors.OperationalError: MySQL Connection not available.

推荐答案

MySQL不支持真正的游标，只模拟他们。因此，您每次只能在每个连接上运行一个游标。

MySQL doesn't support real cursors, and the library only emulates them. As such, you can only run one cursor per connection at a time.

在循环中打开第二个游标，这不是MySQL可以处理的。在使用游标进行新查询之前，请先读取第一个查询的所有列。

In the loop you are opening a second cursor, and that's not something MySQL can handle. Read all rows from the first query before using the cursor for a new query.

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