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How distinct works in sql?

I tried to understand how the distinct (and therefore distinct count) work. I have a data with: While within 1 SessionID there is 1 User_solici. However, there could be multiple SessionID for the same User_solici. For User_solici of “a”, I have Session = 1, 55 and null. I want to find distinct Ses…

Multiple joins on same table

I’m trying to achieve a query which seems simple but I can’t make it work correctly. Here’s my database tables structures: Here’s what i want to achieve: Mutliple members can register to an activity. Then, i group the registrations by tandems. I want a view with all the tandems listed …

Deadlock Exception during select

I am trying to solve a deadlock exception in a spring-boot application running with JPA. I get the following error in the spring boot log. 24 Feb 2020 10:04:11.382 [WARN ] {pool-10-thread-4} [org….

Is there a way I can get output of count values in MySql?

I am dealing with getting the output of some common values. My database is quite big so I am just giving a dummy database here for understanding purposes. Here is the table I have: I have to extract only those variables that have the given common room numbers alotted. This is the table for the required data: …

How can I run this SELECT query?

I’m working on a Messaging feature for an application, and I have a the following tables in MSSQL, along with a User table (not listed): I want to query the ThreadParticipant table for whether or not a thread exists containing only a given set of user ids, let’s say users 1,3,5,7. Each Thread cont…