How to install psycopg2 on windows 7

Question

I have tried pip install psycopg2 and following errors i got:

Error:

(ScrapeProj) C:\Users\e2sn7cy\Documents\GitHub\scraper>pip install psycopg2==2.5.4
Collecting psycopg2==2.5.4
  Using cached psycopg2-2.5.4.tar.gz
    Complete output from command python setup.py egg_info:
    running egg_info
    creating pip-egg-info\psycopg2.egg-info
    writing pip-egg-info\psycopg2.egg-info\PKG-INFO
    writing top-level names to pip-egg-info\psycopg2.egg-info\top_level.txt
    writing dependency_links to pip-egg-info\psycopg2.egg-info\dependency_links.txt
    writing manifest file 'pip-egg-info\psycopg2.egg-info\SOURCES.txt'
    warning: manifest_maker: standard file '-c' not found

    Error: pg_config executable not found.

    Please add the directory containing pg_config to the PATH
    or specify the full executable path with the option:

        python setup.py build_ext --pg-config /path/to/pg_config build ...

    or with the pg_config option in 'setup.cfg'.

    ----------------------------------------
Command "python setup.py egg_info" failed with error code 1 in c:\users\e2sn7cy\appdata\local\temp\pi
p-build-joij3x\psycopg2

Then I tried using easy_install by downloading the .exe file from Stickpole and I got following errors :

(ScrapeProj) C:\Users\e2sn7cy\Envs\ScrapeProj\Scripts>easy_install psycopg2-2.6.1.win-amd64-py2.7-pg9
.4.4-release.exe
Processing psycopg2-2.6.1.win-amd64-py2.7-pg9.4.4-release.exe
psycopg2.tests.test_module: module references __file__
psycopg2.tests.test_types_basic: module references __file__
creating 'c:\users\e2sn7cy\appdata\local\temp\easy_install-sa7asq\psycopg2-2.6.1-py2.7-win32.egg' and
 adding 'c:\users\e2sn7cy\appdata\local\temp\easy_install-sa7asq\psycopg2-2.6.1-py2.7-win32.egg.tmp'
to it
creating c:\users\e2sn7cy\envs\scrapeproj\lib\site-packages\psycopg2-2.6.1-py2.7-win32.egg
Extracting psycopg2-2.6.1-py2.7-win32.egg to c:\users\e2sn7cy\envs\scrapeproj\lib\site-packages
Adding psycopg2 2.6.1 to easy-install.pth file

Installed c:\users\e2sn7cy\envs\scrapeproj\lib\site-packages\psycopg2-2.6.1-py2.7-win32.egg
Processing dependencies for psycopg2==2.6.1
Finished processing dependencies for psycopg2==2.6.1

But when I again tried to install through pip I am getting a new message that its already there :

(ScrapeProj) C:\Users\e2sn7cy\Envs\ScrapeProj>pip install psycopg2
Requirement already satisfied (use --upgrade to upgrade): psycopg2 in c:\users\e2sn7cy\envs\scrapepro
j\lib\site-packages\psycopg2-2.6.1-py2.7-win32.egg

Then I thought ok I should try to import and then I got this error:

(ScrapeProj) C:\Users\e2sn7cy\Envs\ScrapeProj>python
Python 2.7.10 (default, May 23 2015, 09:40:32) [MSC v.1500 32 bit (Intel)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import psycopg2
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\Users\e2sn7cy\Envs\ScrapeProj\lib\site-packages\psycopg2-2.6.1-py2.7-win32.egg\psycopg2\__
init__.py", line 50, in <module>
    from psycopg2._psycopg import BINARY, NUMBER, STRING, DATETIME, ROWID
ImportError: DLL load failed: %1 is not a valid Win32 application.

Now I am not able to understand what to do. Thanks

Edit 1: I have also added my PostgreSQL path to system path variables

path:C:\Program Files\PostgreSQL\9.4

path:C:\Program Files\PostgreSQL\9.4\bin

Answer 1

The correct answer was given by Craig Ringer, I am just adding this because I came to know that we should first check which version of 64 bit or 32bit Python installed on our system. If you have 32 bit version of Python and if you will try to install 64bit, then you will get the above error on importing. For checking the version:

import platform

platform.architecture()

and you will get an output like this:

('32bit','WindowsPE')