Table1 = pd.DataFrame()
Table1['x'] = [x for x in range(10)]
Table2 = pd.DataFrame()
Table2['x'] = [x for x in range(10)]
print(pysqldf(
    """
SELECT 
    *,
    1 as ID 
FROM Table1
UNION
    SELECT *,2 as ID 
    FROM Table2
"""
    ))
Combining two pandas dataframes with just adding the integer count