Using `executemany` to update entries in an existing SQLite3 database (using Python sqlite3)

Question

I know that executemany can be used to conveniently add new entries to a database; useful to reduce the Python method-call overheads compared to single execut

Answer 1

You need to pass a sequence of sequences ([[cont,id], [cont,id], [cont,id], ...], not [cont, cont, cont, ...], [id, id, id, ..]):

for path in paths:
    params = []
    for data in some_computation(path):
        if len(data_ids) >= CHUNKSIZE:
            c.executemany("UPDATE TABLENAME SET cont=? WHERE id=?", params)
            cnx.commit()
            params = []
        params.append([data[1], data[0]])
    if params:
        c.executemany("UPDATE TABLENAME SET cont=? WHERE id=?", params)
    cnx.commit()

Answer 2

what you have is perfect except that you should use zip(conts,ids) where conts and ids are lists. This does the rearrangement automatically for you.