nara-l

git reset --hard HEAD~1
This would delete last commit https://stackoverflow.com/a/1338744

nara-l

# trying to commit without needing to add all those extra files? just clean them

git clean -n -d # to see the files and folders to be deleted first before applying command below

git clean -f -d # -f force clean and -d cleaning directories. git just deletes. 

nara-l

# using truncate

TRUNCATE TABLE table_name RESTART IDENTITY; # to reset index counts

TRUNCATE TABlE table_name CASCADE; # to delete foreign key dependencies

nara-l

# We want to get the keys which failed this could be applied to other situations
# Python 3
dict_of_elements = {1: 'john', 2: 'peter', 3: 'luke', 4: 'mark'}  # can equally be a list?
failed_keys = set()
for list in dict_of_elements:
    try:
        dict_of_elements[9]  # trying to access keys that don't exist
    except Exception as e:
        f_k = e.args[0]
        failed_keys.add(f_k)

nara-l

# After an import of data sometimes when you try to create new records, postgres creates same ids and cause clashes from time to time
# To correct the sequence and tell postgres where to start counting next run this


SELECT pg_catalog.setval(pg_get_serial_sequence('table_name', 'id'), MAX(id)) FROM table_name; # replace table_name with required table

nara-l

git fetch origin         # gets latest changes made to master
git checkout branch_name     # switch to your branch
git merge master         # merge with master
# manually resolve any merge conflicts here
git push origin branch_name  # push branch and update the pull request

# branch_name is the name of the branch you you have the conflict on

nara-l

Recently upgraded to lattest version of High sierra and had permission issues in trying to upgrade node

sudo chown -R $(whoami) /usr/local          # does not work any more


sudo chown -R $(whoami) $(brew --prefix)/*     # this works

nara-l

CREATE DATABASE newdb WITH TEMPLATE originaldb OWNER dbuser;  # newdb and originaldb are names of the new database and old database

# getting an error ?
ERROR:  source database "originaldb" is being accessed by other users

# run this query to stop error before running create data base query

SELECT pg_terminate_backend(pg_stat_activity.pid) FROM pg_stat_activity 
WHERE pg_stat_activity.datname = 'originaldb' AND pid <> pg_backend_pid();  # change originaldb with name of old database

nara-l

https://stackoverflow.com/questions/32812463/setting-schema-for-all-queries-of-a-connection-in-psycopg2-getting-race-conditi

cheat sheet
http://www.postgresqltutorial.com/postgresql-cheat-sheet/

Postgres setup with django

nara-l

SELECT COUNT(*) FROM (SELECT DISTINCT column_name FROM table_name) AS temp;