python list in sql query as parameter

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imploding a list for use in a python MySQLDB IN clause (8 answers)

Closed 4 months ago.

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

select name from students where id = |IN THE LIST l|

How do I accomplish this?

Answer 1

Answers so far have been templating the values into a plain SQL string. That's absolutely fine for integers, but if we wanted to do it for strings we get the escaping issue.

Here's a variant using a parameterised query that would work for both:

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)

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

Dont complicate it, Solution for this is simple.

l = [1,5,8]

l = tuple(l)

params = {'l': l}

cursor.execute('SELECT * FROM table where id in %(l)s',params)

I hope this helped !!!

Answer 4

The SQL you want is

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

If you want to construct this from the python you could use

l = [1, 5, 8]
sql_query = 'select name from studens where id in (' + ','.join(map(str, l)) + ')'

The map function will transform the list into a list of strings that can be glued together by commas using the str.join method.

Alternatively:

l = [1, 5, 8]
sql_query = 'select name from studens where id in (' + ','.join((str(n) for n in l)) + ')'

if you prefer generator expressions to the map function.

UPDATE: S. Lott mentions in the comments that the Python SQLite bindings don't support sequences. In that case, you might want

select name from studens where id = 1 or id = 5 or id = 8

Generated by

sql_query = 'select name from studens where ' + ' or '.join(('id = ' + str(n) for n in l))

Answer 5

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 6

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 7

If you're using PostgreSQL with the Psycopg2 library you can let its tuple adaption do all the escaping and string interpolation for you, e.g:

ids = [1,2,3]
cur.execute(
  "SELECT * FROM foo WHERE id IN %s",
  [tuple(ids)])

i.e. just make sure that you're passing the IN parameter as a tuple. if it's a list you can use the = ANY array syntax:

cur.execute(
  "SELECT * FROM foo WHERE id = ANY (%s)",
  [list(ids)])

note that these both will get turned into the same query plan so you should just use whichever is easier. e.g. if your list comes in a tuple use the former, if they're stored in a list use the latter.

Answer 8

Solution for @umounted answer, because that broke with a one-element tuple, since (1,) is not valid SQL.:

>>> random_ids = [1234,123,54,56,57,58,78,91]
>>> cursor.execute("create table test (id)")
>>> for item in random_ids:
    cursor.execute("insert into test values (%d)" % item)
>>> sublist = [56,57,58]
>>> cursor.execute("select id from test where id in %s" % str(tuple(sublist)).replace(',)',')'))
>>> a = cursor.fetchall()
>>> a
[(56,), (57,), (58,)]

Other solution for sql string:

cursor.execute("select id from test where id in (%s)" % ('"'+'", "'.join(l)+'"'))

Answer 9

placeholders= ', '.join("'{"+str(i)+"}'" for i in range(len(l)))
query="select name from students where id (%s)"%placeholders
query=query.format(*l)
cursor.execute(query)

This should solve your problem.

Answer 10

Just use inline if operation with tuple function:

query = "Select * from hr_employee WHERE id in " % tuple(employee_ids) if len(employee_ids) != 1 else "("+ str(employee_ids[0]) + ")"

Answer 11

To run a select from where field is in list of strings (instead of int), as per this question use repr(tuple(map(str, l))). Full example:

l = ['a','b','c']
sql = f'''

select name 
from students 
where id in {repr(tuple(map(str, l)))}
'''
print(sql)

Returns: select name from students where id in ('a', 'b', 'c')

For a list of dates in Oracle, this worked

dates_str = ','.join([f'DATE {repr(s)}' for s in ['2020-11-24', '2020-12-28']])
dates_str = f'({dates_str})'

sql_cmd = f'''
select *
from students 
where 
and date in {dates_str}
'''

Returns: select * from students where and date in (DATE '2020-11-24',DATE '2020-12-28')

Answer 12

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 13

a simpler solution:

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

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

Answer 14

l = [1] # or [1,2,3]

query = "SELECT * FROM table WHERE id IN :l"
params = {'l' : tuple(l)}
cursor.execute(query, params)

The :var notation seems simpler. (Python 3.7)

Answer 15

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 16

This Will Work If Number of Values in List equals to 1 or greater than 1

t = str(tuple(l))
if t[-2] == ',':
   t= t.replace(t[-2],"")
query = "select name from studens where id IN {}".format(t)