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mysql query from backend python server syntax error with backticks on table name [duplicate]

Pretty new to sqlite3, so bear with me here..
I'd like to have a function to which I can pass the table name, and the values to update.
I initially started with something like this:
def add_to_table(table_name, string):
cursor.execute('INSERT INTO {table} VALUES ({var})'
.format(
table=table_name,
var=string)
)
Which works A-OK, but further reading about sqlite3 suggested that this was a terribly insecure way to go about things. However, using their ? syntax, I'm unable to pass in a name to specify the variable.
I tried adding in a ? in place of the table, but that throws a syntax error.
cursor.execute('INSERT INTO ? VALUES (?)', ('mytable','"Jello, world!"'))
>> >sqlite3.OperationalError: near "?": syntax error
Can the table in an sql statement be passed in safely and dynamically?

Its not the dynamic string substitution per-se thats the problem. Its dynamic string substitution with an user-supplied string thats the big problem because that opens you to SQL-injection attacks. If you are absolutely 100% sure that the tablename is a safe string that you control then splicing it into the SQL query will be safe.
if some_condition():
table_name = 'TABLE_A'
else:
table_name = 'TABLE_B'
cursor.execute('INSERT INTO '+ table_name + 'VALUES (?)', values)
That said, using dynamic SQL like that is certainly a code smell so you should double check to see if you can find a simpler alternative without the dynamically generated SQL strings. Additionally, if you really want dynamic SQL then something like SQLAlchemy might be useful to guarantee that the SQL you generate is well formed.

Composing SQL statements using string manipulation is odd not only because of security implications, but also because strings are "dumb" objects. Using sqlalchemy core (you don't even need the ORM part) is almost like using strings, but each fragment will be a lot smarter and allow for easier composition. Take a look at the sqlalchemy wiki to get a notion of what I'm talking about.
For example, using sqlsoup your code would look like this:
db = SQLSoup('sqlite://yourdatabase')
table = getattr(db, tablename)
table.insert(fieldname='value', otherfield=123)
db.commit()
Another advantage: code is database independent - want to move to oracle? Change the connection string and you are done.

Use of '.format()' vs. '%s' in cursor.execute() for mysql JSON field, with Python mysql.connector,

My objective is to store a JSON object into a MySQL database field of type json, using the mysql.connector library.
import mysql.connector
import json
jsonData = json.dumps(origin_of_jsonData)
cnx = mysql.connector.connect(**config_defined_elsewhere)
cursor = cnx.cursor()
cursor.execute('CREATE DATABASE dataBase')
cnx.database = 'dataBase'
cursor = cnx.cursor()
cursor.execute('CREATE TABLE table (id_field INT NOT NULL, json_data_field JSON NOT NULL, PRIMARY KEY (id_field))')
Now, the code below WORKS just fine, the focus of my question is the use of '%s':
insert_statement = "INSERT INTO table (id_field, json_data_field) VALUES (%s, %s)"
values_to_insert = (1, jsonData)
cursor.execute(insert_statement, values_to_insert)
My problem with that: I am very strictly adhering to the use of '...{}'.format(aValue) (or f'...{aValue}') when combining variable aValue(s) into a string, thus avoiding the use of %s (whatever my reasons for that, let's not debate them here - but it is how I would like to keep it wherever possible, hence my question).
In any case, I am simply unable, whichever way I try, to create something that stores the jsonData into the mySql dataBase using something that resembles the above structure and uses '...{}'.format() (in whatever shape or form) instead of %s. For example, I have (among many iterations) tried
insert_statement = "INSERT INTO table (id_field, json_data_field) VALUES ({}, {})".format(1, jsonData)
cursor.execute(insert_statement)
but no matter how I turn and twist it, I keep getting the following error:
ProgrammingError: 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '[some_content_from_jsonData})]' at line 1
Now my question(s):
1) Is there a way to avoid the use of %s here that I am missing?
2) If not, why? What is it that makes this impossible? Is it the cursor.execute() function, or is it the fact that it is a JSON object, or is it something completely different? Shouldn't {}.format() be able to do everything that %s could do, and more?

First of all: NEVER DIRECTLY INSERT YOUR DATA INTO YOUR QUERY STRING!
Using %s in a MySQL query string is not the same as using it in a python string.
In python, you just format the string and 'hello %s!' % 'world' becomes 'hello world!'. In SQL, the %s signals parameter insertion. This sends your query and data to the server separately. You are also not bound to this syntax. The python DB-API specification specifies more styles for this: DB-API parameter styles (PEP 249). This has several advantages over inserting your data directly into the query string:
Prevents SQL injection
Say you have a query to authenticate users by password. You would do that with the following query (of course you would normally salt and hash the password, but that is not the topic of this question):
SELECT 1 FROM users WHERE username='foo' AND password='bar'
The naive way to construct this query would be:
"SELECT 1 FROM users WHERE username='{}' AND password='{}'".format(username, password)
However, what would happen if someone inputs ' OR 1=1 as password. The formatted query would then become
SELECT 1 FROM users WHERE username='foo' AND password='' OR 1=1
which will allways return 1. When using parameter insertion:
execute('SELECT 1 FROM users WHERE username=%s AND password=%s', username, password)
this will never happen, as the query will be interpreted by the server separately.
Performance
If you run the same query many times with different data, the performance difference between using a formatted query and parameter insertion can be significant. With parameter insertion, the server only has to compile the query once (as it is the same every time) and execute it with different data, but with string formatting, it will have to compile it over and over again.

In addition to what was said above, I would like to add some details that I did not immediately understand, and that other (newbies like me ;)) may also find helpful:
1) "parameter insertion" is meant for only for values, it will not work for table names, column names, etc. - for those, the Python string substitution works fine in the sql syntax defintion
2) the cursor.execute function requires a tuple to work (as specified here, albeit not immediately clear, at least to me: https://dev.mysql.com/doc/connector-python/en/connector-python-api-mysqlcursor-execute.html)
EXAMPLE for both in one function:
def checkIfRecordExists(column, table, condition_name, condition_value):
...
sqlSyntax = 'SELECT {} FROM {} WHERE {} = %s'.format(column, table, condition_name)
cursor.execute(sqlSyntax, (condition_value,))
Note both the use of .format in the initial sql syntax definition and the use of (condition_value,) in the execute function.

Syntax error when inserting strings into MySQL using PyMySQL

I frequently use pymysql to insert data into a MySQL server.
When inserting strings, I usually (but not every time) receive: pymysql.err.ProgrammingError: (1064, ...) when I insert a string using the code (where refers to a varchar):
cursor.execute("Insert into table (column) values (%s)", (stringVar))
Typically I have to do something like:
cursor.execute("Insert into table (column) values ('"+stringVar+"')"))
However, sometimes that throws the same error and I have to do something like:
stringVar="'"+stringVar
stringVar=stringVar+"'"
cursor.execute("Insert into table (column) values ("+stringVar+")")
This just isn't a feasible way to program this operation.
I assume I am messing up something simple but I cannot figure out what this is. I use pymysql a lot and this error is really starting to wear on me. Any help would be much appreciated!

cursor.execute('INSERT INTO table (column) VALUES (?)', (stringVar,))
Whenever you're trying to directly format a string into a query like that, it's basically always a sign you're doing something wrong. Every python database interface I'm aware of has a way to pass parameters to queries like above. Note that having the stringVar contained within an iterable is required.

How to handle apostrophes in MySQL-Python?

A Python API is giving back u"'HOPPE'S No. 9'" as a value for a particular product attribute. I'm then looking to insert it into the DB, also using Python (python-mysqldb), with the following query:
INSERT INTO mytable (rating, Name) VALUES('5.0 (7)', 'HOPPE'S No. 9';
MySQL rejects this, and the suggested approach to handling a single quote in MySQL is to escape it first. This I need to do in Python, so I try:
In [5]: u"'HOPPE'S No. 9'".replace("'", "\'")
Out[5]: u"'HOPPE'S No. 9'"
When I incorporate this in my program, MySQL still rejects it. So I double-escape the apostrophe, and then an insert happens successfully. Thing is, it contains the escape character (so what gets written is 'HOPPE\'S No. 9').
If I need the second escape character, but when I add it gets left in, then how can I handle the escaping without having the escape character included in the string that gets inserted?
Edit: Based on theBjorn's suggestion, tried:
actualSQL = "INSERT INTO %s (%s) VALUES(%s);"
#cur.execute(queryString)
cur.execute(actualSQL,
(configData["table"], sqlFieldMappingString, sqlFieldValuesString))
but it looks like I'm back to where I was when I was trying to escape using the single escape with .replace():
Error 1064: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ''mytable' ('rating, Name, Image, mfg, price, URL') VALUES('\'5.0 (3)\', \'AR-1' at line 1

You should never construct sql that way. Use parameterized code instead:
cursor.execute(
"insert into mytable (rating, name) values (%s, %s);",
("5.0 (7)", "HOPPE'S No. 9")
)
your latest problem is due to the misconception that this is string interpolation, which it isn't (the use of %s is confusing), thus:
actualSQL = "INSERT INTO %s (%s) VALUES(%s);"
will be wrong. It is possible to construct your sql string, but probably easier to do so in two steps so we don't trip over sql parameter markers looking like string interpolation markers. Assuming you have the values in a tuple named field_values:
params = ["%s"] * len(field_values) # create a list with the correct number of parameter markers
sql = "insert into %s (%s) values (%s)" % ( # here we're using string interpolation, but not with the values
configData["table"],
sqlFieldMappingString,
', '.join(params)
)
if you print sql it should look like my example above. Now you can execute it with:
cursor.execute(sql, field_values)

Python mySQL - escaping quotes

I have seen this question asked in various ways on this website, but none of them exactly addressed my issue.
I have an sql statement with single quotes inside it, and am trying to use recommended practices before making database queries with it. So the statement is like
val2="abc 'dostuff'"
sql="INSERT INTO TABLE_A(COL_A,COL_B) VALUES(%s,'%s')" %(val1, val2)
a_cursor.execute(sql)
However, when I run this, I get..
ProgrammingError: (1064,"You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'dostuff'.
What am I doing wrong?
Thanks very much
Nupur

Use parameters instead of string interpolation to ensure that your values are properly escaped by the database connector:
sql = "INSERT INTO TABLE_A(COL_A,COL_B) VALUES(%s, %s)"
a_cursor.execute(sql, (val1, val2))
The mysqldb sql parameter style uses the same syntax as used by the python string formatting operator, which is a little confusing.