Pandas read_sql with where 子句使用“in”

Question

Help!

I need to query a table with an "in" clause, where the SQL looks like this:

select * from some_table where some_field in (?)

I originally took a naive approach and tried this:

in_items = [1,2,3,4]
df = pd.read_sql(MY_SQL_STATEMENT, con=con, params=[in_items]

Which did not work, it throws the following error:

The SQL contains 1 parameter markers, but 4 parameters were supplied

Where I'm stuck at, is figuring out how to pass a list of items as a single parameter.

I can do a string concatenation approach, something like:

MY_SQL = 'select * from tableA where fieldA in ({})'.format(
  ','.join([str(x) from x in list_items]))
df = pd.read_sql(MY_SQL, con=con)

I would rather avoid this approach if possible. Does anybody know of a way to pass a list of values as a single parameter?

I'm also open to a possibly more cleverer way to do this. :)

Answer 1

Simply string format the placeholders then pass in your params into pandas.read_sql . Do note, placeholder markers depend on DB-API: pyodbc / sqlite3 uses qmarks ? and most others use %s . Below assumes the former marker:

in_items = [1,2,3,4]
MY_SQL = 'select * from tableA where fieldA in ({})'\
           .format(', '.join(['?' for _ in in_items]))
# select * from tableA where fieldA in (?, ?, ?, ?)

df = pd.read_sql(MY_SQL, con=con, params=[in_items])

Answer 2

For me, using sqllite3, worked this way:

list_of_entries_to_retrive = pd.read_excel('.table_with_entries.xlsx')
list_of_entries_to_retrive = (cell_list['entries']).tolist()

conn = sqlite3.connect('DataBase.db')

queryString = 'SELECT * FROM table WHERE attribute IN (\'{}\');'.format('\',\''.join([_ for _ in list_of_entries_to_retrive]))
df = pd.read_sql(queryString, con=conn)

Do not worked this way:

df = pd.read_sql(queryString, con=conn,  params=[list_of_entries_to_retrive]))

Thanks