mysql-connector python 'IN' operator stored as list

Question

I am using mysql-connector with python and have a query like this:

SELECT avg(downloadtime) FROM tb_npp where date(date) between %s and %s and host like %s",(s_date,e_date,"%" + dc + "%")

NOw, if my variable 'dc' is a list like this:

 dc = ['sjc','iad','las']

Then I have a mysql query like below:

SELECT avg(downloadtime) FROM tb_npp where date(date) = '2013-07-01' and substring(host,6,3) in ('sjc','las');

My question is, how do I write this query in my python code which will convert my variable 'dc' to a list?

I tried the below query but getting error: Failed processing format-parameters; 'MySQLConverter' object has no attribute '_list_to_mysql'

cursor3.execute("SELECT avg(downloadtime) FROM tb_npp where date(date) between %s and %s and substring(host,6,3) in %s",(s_date,e_date,dc))

Can somebody please tell me what I am doing wrong?

Thanks in advance

Answer 1

I'm not familiar with mysql-connector, but its behavior appears to be similar to MySQLdb in this regard. If that's true, you need to use a bit of string formatting:

sql = """SELECT avg(downloadtime) FROM tb_npp where date(date) = %s 
         and substring(host,6,3) in ({c})""".format(
            c=', '.join(['%s']*len(dc)))    
args = ['2013-07-01'] + dc
cursor3.execute(sql, args)

Answer 2

As an alternative to @unutbu's answer which is specific to using mysql-connector:

cursor.execute(
    "SELECT thing "
    "    FROM table "
    "    WHERE some_col > %(example_param)s " 
    "    AND id IN ({li})".format(li=", ".join(list_of_values)),
    params={
        "example_param": 33
    })

If you try to move the joined list into a param (like example param) it may complain because mysql-connector interprets the values as strings.

If your list isn't made up of things that are string-format-able (like integers) by default then in your join statement replace list_of_values with:

[str(v) for v in list_of_values]