In contrast to CHAR, VARCHAR values are stored as a 1-byte or 2-byte length prefix plus data. The length prefix indicates the number of bytes in the value. A column uses one length byte if values require no more than…
I am trying to implement an appointment manager for a dentist office. Thing is I am not sure how to properly implement such function. Right now I have managed to create these two tables that will handle it: CREATE TABLE…
I’m building a to-do app in React with a Node.js/Express backend and PostgreSQL as my database. The app allows users to add, edit, and delete tasks, which are stored in the database. The problem I’m facing is with editing tasks:…
I'm doing this StrataScratch SQL question. The suggested solution uses two subqueries for each max value of each department, and then it substracts them to get the absolute value. I wanted to solve this question using dense_rank/rank window function by…
I'm working with PostgreSQL and using pg_export_snapshot() to create a snapshot in one transaction, which I then import into another transaction using SET TRANSACTION SNAPSHOT. I noticed that PostgreSQL requires the original (exporting) transaction to stay active while the snapshot…
I am having hard times visualizing my sqlite database , i am using react native under expo with drizzle ORM to manage a sqlite database locally , the issues is that when i run all the setup commands it says…
I'm new to node.js and MongoDB. Installed all packages as says in a YouTube tutorial. I tried a lot to connect **MongoDB **with node.js. but, there is no error messages and not connected. I have downloaded **Mongo Shell ** also.…
I'm revisiting an old question from 16 years ago about PostgreSQL HASH indexes vs B-TREEs. At the time, it seemed like HASH indexes were far less efficient than B-TREEs in terms of both space and time and the consensus was…
I'm writing a solution for a DataLemur SQL question and I almost had it right but there is one row missing. I have written this query myself: WITH CTE AS ( SELECT user_id, transaction_date, DENSE_RANK() OVER (PARTITION BY user_id order…
As the title describes I want to have a zero-or-one to zero-or-one relationship. For example, let's say we have two tables Calls and Files. A call might have an attached file on it, and vice versa. But I have a…