python list in sql query as parameter

Question

I have a python list, say l

l = [1,5,8]

I want to write a sql query to get the data for all the elements of the list, say

s         


        

Answer 1

I like bobince's answer:

placeholder= '?' # For SQLite. See DBAPI paramstyle.
placeholders= ', '.join(placeholder for unused in l)
query= 'SELECT name FROM students WHERE id IN (%s)' % placeholders
cursor.execute(query, l)

But I noticed this:

placeholders= ', '.join(placeholder for unused in l)

Can be replaced with:

placeholders= ', '.join(placeholder*len(l))

I find this more direct if less clever and less general. Here l is required to have a length (i.e. refer to an object that defines a __len__ method), which shouldn't be a problem. But placeholder must also be a single character. To support a multi-character placeholder use:

placeholders= ', '.join([placeholder]*len(l))

Answer 2

Easiest way is to turn the list to tuple first

t = tuple(l)
query = "select name from studens where id IN {}".format(t)

Answer 3

string.join the list values separated by commas, and use the format operator to form a query string.

myquery = "select name from studens where id in (%s)" % ",".join(map(str,mylist))

(Thanks, blair-conrad)

Answer 4

For example, if you want the sql query:

select name from studens where id in (1, 5, 8)

What about:

my_list = [1, 5, 8]
cur.execute("select name from studens where id in %s" % repr(my_list).replace('[','(').replace(']',')') )

Answer 5

This uses parameter substitution and takes care of the single value list case:

l = [1,5,8]

get_operator = lambda x: '=' if len(x) == 1 else 'IN'
get_value = lambda x: int(x[0]) if len(x) == 1 else x

query = 'SELECT * FROM table where id ' + get_operator(l) + ' %s'

cursor.execute(query, (get_value(l),))

Answer 6

a simpler solution:

lst = [1,2,3,a,b,c]

query = f"""SELECT * FROM table WHERE IN {str(lst)[1:-1}"""