Get a CSV file from a SQL query using batches of 1000 lines

get_csv_by_1000.py

import sys
import pyodbc as odbc
import datetime

dsn = sys.argv[1]
query_file = sys.argv[2]
csv_file = sys.argv[3]

print(f'Connecting to {dsn}')
print(f'Executing {query_file}')
print(f'Saving to {csv_file}\n')

conn = odbc.connect(dsn)
cursor = conn.cursor()
cursor.execute(open(query_file).read())
print('Query executed. Fetching results...\n')
if sys.argv[4] == '--debug': print(cursor.description)
counter = 0
with open(csv_file, 'w') as f:
    columns = list(zip(*cursor.description))[0]
    c_size = len(columns)
    data = {}
    for i, v in enumerate(columns):
        f.write(v)    
        if i < c_size - 1: f.write(';')
    f.write('\n')
    while True:
        rows = cursor.fetchmany(1000) 
        for row in rows:
            counter += 1
            if not row:
                break
            else:
                for i, v in enumerate(columns):
                    reg = row[i]
                    if type(reg) == datetime.datetime: reg = reg.isoformat() 
                    data[v] = reg
                    f.write(str(reg))
                    if i < c_size - 1: f.write(';')
                f.write('\n')
                if counter % 5000 == 0:
                    sys.stdout.write(f'\rProcessing line {counter} of {cursor.rowcount}.')
print('\nDone!\n')