How to install psycopg2 on windows 7 - postgresql

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')

Answer 2

Download the pre-packaged binary release of psycopg2 for Windows rather than compiling it yourself. It's a pain to compile on Windows. This is explained in the install documentation for psycopg2.
You might need to remove your half-installed attempts.

Answer 3

Choose the appropriate version from this page:
http://www.stickpeople.com/projects/python/win-psycopg/
Right click and select copy link address
Back at home, use easy_install <<Paste URL Here>>
Freeze your new requirements: pip freeze > requirements.txt

Answer 4

Now that psycopg is in PyPI (as of March 2017 it appears), just fire up a command prompt with administrator privileges and install like so:
python -m pip install -U pip
python -m pip install psycopg2
If you don't have pip installed, follow the instructions here to do that first:
https://stackoverflow.com/a/12476379/2540707

Answer 5

pip install psycopg2-binary
This worked for me

Answer 6

Step 1: Compilers Installation and configuration
https://wiki.python.org/moin/WindowsCompilers
Before do anything, install or upgrade the Setuptools Python package. It contain compatibility improvements and add automatic use of compilers:
pip install --upgrade setuptools
Step 2: Download and install PostgreSQL
Before you continue to install python packages inside you virtualenvs download postgres itself. It contains files that are needed when compiling the psycopg2 python package. Just use the PostgreSQL installer(version 10 for example).
Important: add the postgres C:\Program Files\PostgreSQL\10\bin folder to your path. It contains the .dll needed for psycopg2.
Step 3: Install psycopg2
pip install psycopg2
Tested on Windows 7 + python 3.7

Answer 7

The best/easiest way of installing packages (including this problematic psycopg2 ) for python on windows platform is to:
1) install anaconda and ...
2) use Anaconda Navigator GUI to install/update packages.
By this one avoids many inconsistencies and conflicts that occurs among different packages versions and installations.