Ihor Romanchenko questions

Ihor Romanchenko answers

• select from ... - based on a value in JSON format
• SQL sum of column value, unique per user per day
• can we select and update to database together?
• PostgreSQL database size is less after backup/load on Heroku
• Sum(Case when) resulting in multiple rows of the selection
• How to add a foreign key constraint to same table using ALTER TABLE in PostgreSQL
• How to render one to many relationships to XML with PostgreSQL
• Why should we use rollback in sql explicitly?
• How to use postgres ::date with knex.js
• Autoincrement separately for each foreign key