Python pymysql - iterate through mysql table key and value

Question

I am new to python pymysql (I used before Ruby with Mysql2 gem), I want to get the key and the value from mysql table and do some actions:

For example:

dbconnection = pymysql.connect(host=mysql_hostname, user=mysql_username, password=mysql_pass, db=mysql_schema, charset='utf8mb4', cursorclass=pymysql.cursors.DictCursor)
cursor = dbconnection.cursor()
_SQL = (""" 
        select * ...
        """)

cursor.execute(_SQL)
result = cursor.fetchall()
for row in result:
    print(row)
    print("\n")
    # How can I access each key and each value for example: STATUS is the value and 3 is the key
    # I want to do something like this: 
    #'if the value of 'CAP' > 1: change the value of status where the ID key
    #   cursor.execute("UPDATE <table> SET row[STATUS]='1' WHERE ID='row[ID]'")

Output:

{'STATUS': 3, 'ID': 10, 'CAP': 1}
{'STATUS': 3, 'ID': 11, 'CAP': 2}
{'STATUS': 3, 'ID': 12, 'CAP': 3}

Thanks

What do you mean with the key and value **of a table**? A table can have multiple columns. — Willem Van Onsem, Feb 27 '17 at 12:31
I update my question, I want to be able to access the key name and the value name for each result — Berlin, Feb 27 '17 at 12:35

score 4 · Accepted Answer · answered Feb 27 '17 at 12:37

4

A row is simply a dictionary. So you can use .items() to generate a sequence of key and value:

for row in result:
    for key,value in row.items():
        print('The key is %s'%key)
        print('The value is %s'%value)

answered Feb 27 '17 at 12:37

Willem Van Onsem

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right :), it is a bit confusing when switching from Ruby to Python, do you maybe know if its ok to use 'pymysql' instead of `MySQL Connector` ? – Berlin Feb 27 '17 at 12:46
@Berlin: unfortunately I'm not very familiar with database frameworks, etc. – Willem Van Onsem Feb 27 '17 at 12:47
Could you provide a complete example. With `cursor. fetchall()` this does not work. – user3072843 Dec 13 '21 at 14:08

score 2 · Answer 2 · answered Nov 26 '17 at 12:38

Using pymysql, you need to declare the cursor as a dictionary type like below:

import pymysql

connection = pymysql.connect(host="localhost", user="root", passwd="", database="myraces")
#  cursor = connection.cursor()
cursor = pymysql.cursors.DictCursor(connection)

query = "SELECT * FROM `races`"
cursor.execute(query)
rows = cursor.fetchall()
for row in rows:
    for key, value in row.items():
        print(key, value)

score 1 · Answer 3 · answered Feb 27 '17 at 13:53

1

The code you are looking for is this:

for row in result:
    if row["CAP"] > 1:
        cursor.execute("UPDATE <table> SET row[STATUS]='1' WHERE ID='row[ID]'")
    else:
        continue

answered Feb 27 '17 at 13:53

Meghdeep Ray

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Python pymysql - iterate through mysql table key and value

3 Answers3