Gist illustrating how to connect to a GE Proficy iHistorian OLEDB instance from Python. This uses the PyADO library (http://pyado.sourceforge.net).

gistfile1.py

import PyADO

#print help(PyADO.connect)

conn = PyADO.connect(None,host='localhost',user='',password='',provider='iHOLEDB.iHistorian.1')
print conn

curs = conn.cursor()
curs.execute("SELECT * FROM ihTags")

result = curs.fetchall()
descr = curs.description
for col in descr:
    print col[0],

print

for row in result:
    for col in row:
        print col,
    print

curs.close()
conn.close()

hello,I run your code in my computer recently,However,the code get exception:
pywintypes.com_error: (-2147352567, '发生意外。', (0, 'ADODB.Connection', '对象关闭时，不允许操作。', 'C:\WINDOWS\HELP\ADO270.CHM', 1240653, -2146824584), None)

I find all kinds of method for this,but not sovle it.Do you know the problem of it?please help me.thanks for your consideration