SQL in Python: how to debug / print for an sql query with variables (%s)

Question

I'm using mysql.connector and Python 3.7.

For SQL queries, I use this method:

cursor.execute("INSERT INTO table VALUES (%s, %s, %s)", (var1, var2, var3))

The thing is... when I want to print or debug the entire sql query, I can't get the values instead of the %s (I know the whole point is that you can't).

How do you guys do to debug this, then?

Thanks.

Doesn't print("INSERT INTO table VALUES (%s, %s, %s)" % (var1, var2, var3)) work? — PaulS
– PaulS, Commented Feb 3, 2020 at 12:26
I use string formatting and print it print("INSERT INTO table VALUES ({0}, {1}, {2})".format((var1, var2, var3)) — Y.S
– Y.S, Commented Feb 3, 2020 at 12:30
@PaulS I'm gonna look into that. Thank you. Edit: that does work. However how could I get the query that is being sent through the cursor at doing cursor.execute? — andopr
– andopr, Commented Feb 3, 2020 at 12:31
@Y.S That's the method we were using before this, but heard its insecure? — andopr
– andopr, Commented Feb 3, 2020 at 12:32
@andopr if you just print it out to the console, and not passing the formatted string as a sql statement, i'm not sure security is a concern. — Y.S
– Y.S, Commented Feb 3, 2020 at 12:34

PaulS · Accepted Answer · 2020-02-03 12:35:19Z

3

The syntax for printing formatted strings is the following:

name = "John"
print("Hello, %s!" % name)

You can apply that to your SQL statement and print it like this:

print("INSERT INTO table VALUES (%s, %s, %s)" % (var1, var2, var3))

answered Feb 3, 2020 at 12:35

PaulS

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Miad Dehghani · Accepted Answer · 2025-04-03 10:09:00Z

0

One thing I would like to add to PaulS' answer is that if any of your variables are strings, you should put the %s associated with that variable inside quotes.

var1 = str()
var2 = int()
var3 = float()

print("INSERT INTO table VALUES ('%s', %s, %s)" % (var1, var2, var3))

edited Apr 3 at 10:09

answered Apr 3 at 10:06

Miad Dehghani

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