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Tag: having-clause

SQL Select from many-to-one

I have two tables containing a one-to-many relationship. How should I select the “one” side given information for the “many” side? I’m using SQLite. Let’s say our first table, T1, is about cars and the second table, T2, is about the imperfections in each car. Let’s say we can describe the imperfections with an integer. So we have: We have

Can this be done as a SQL VIEW

I have a SQL Server table of Customer’s Events: There can be many EventTypes for the same customer in one day. EventTypes are like 1 – CheckIn 2 – CheckOut 3 – ExamStart 4 – ExamEnd Now I want to select Customers that are currently (today) on premises. That’s Clients who had checked in, but hadn’t checked out, no matter

MySQL: Why are these two wrong? (Invalid use of group function, selected nothing after using having())

Credit:Leetcode_1076.Project Employees II Here is the sample table Project table: (project_id, employee_id) is the primary key of this table. I have tried several methods and managed to find the right one by using dense_rank(); however, I still don’t understand why these two syntaxes are wrong to select project_id with the largest number of employees: 1.Return null: {“headers”: [“project_id”, “n”], “values”:

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