CODEWITHSUNDEEP
pythonmysql
Matthijs Kramer
Matthijs Kramer

Reputation: 584

Unable to unpack pymysql query result to variables

I'm using a script that collects data from a database. I wanted to refine the script a bit, but ran into trouble.

I'm running a query that I know will ALWAYS return only one row with 3 values in it. I want to unpack those values into separate variables, but only the last seems to actually have some sort of value.

Here's my code:

import pymysql

cnx = pymysql.connect(host=dbHost, database=dbName, user=dbUser, passwd=dbPass)
query = "select id_parameter,unit,shortname from t_list_metpara where shortname='TT'"

with cnx.cursor() as cursor1:
    cursor1.execute(query)
    row = cursor1.fetchone()

cnx.close()
id_parameter, unit, shortname = row[:3]

print(row)
print(id_parameter, unit, shortname)
print([type(v) for v in [id_parameter, unit, shortname]])
print([row[v] for v in [0, 1, 2]])

and the result:

(1, '°C\r', 'tt')
 tt
[<class 'int'>, <class 'str'>, <class 'str'>]
[1, '°C\r', 'tt']

Can anyone explain to my why Python (or the pymysql package) behaves this way, and what I can do to avoid it?

Upvotes: 0

Views: 89

Answers (1)

Daniel Roseman
Daniel Roseman

Reputation: 599926

This has nothing to do with pymysql, or even Python itself, and there is nothing wrong with your variables.

\r means a carriage return character. If you print something followed by a \r, the cursor position will return to the start of the line; the next character will begin from the start of that line. If you printed each of id_paramter, unit and shortname separately, you would see all the data.

Upvotes: 1

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