I’m studying to interview for a job involving a lot of SQL. I’ve noticed a few exercises that revolve around returning values based on a sequence across rows, and I would love to know if there’s a standard way of doing this. Something akin to the subquery below I’ve found useful for selecting a max/min value: Here’s a relevant example
Tag: window-functions
Count rows with equal values in a window function
I have a time series in a SQLite Database and want to analyze it. The important part of the time series consists of a column with different but not unique string values. I want to do something like this: I don’t know how to get the countValue column. It should count all Values of the partition equal to the current
Order by column having duplicates for aggregation
Employees Table Question: Why does ordering by a column having duplicates produce final values instead of intermediate values? For e.g. when this query is executed, 3 employees having salary = 5000, the final value i.e. the value that should be produced for the 3rd employee is produced for the 1st? Answer SQL window functions have a window frame clause that
If ID has both values A and B it should return AB
INPUT: ID VALUES 1 A 1 B 2 A 3 B OUTPUT: ID VALUES 1 AB 1 AB 2 A 3 B If ID has both values A and B it should return AB.
Min and max value per group keeping order
I have a small problem in Redshift with with grouping; I have a table like following: INPUT VALUE CREATED UPDATED ———————————— 1 ‘2020-09-10’ ‘2020-09-11’ …
How to incrementally count the number of repeated instances
I want to incrementally count the number of repeated instances in a table, so if I have a table like this: Using the column “name” as reference, the output would be The DBMS implementation is MySQL, version 5.6 Answer In MySQL 5.x, where window functions are not available, one option uses a correlated subquery: You could also do this with
Sum whole column plus a single row of another column and display in a third column
here is my problem i do have a query the returns to me this table what i need is to sum all the organic_value where the previa is the same + financial_value of each month so the final table would be any tips how to tackle this problem? Answer That’s a window sum:
Using rank to enumerate the session
Hi can anyone help me for this. What im trying to do is to rank my session id but it seems not to work as it returns me just “1”. The third row should be 2, the row 5 should have 2 for rank and the row 6 should have 3 for rank and so on. I try to enumerate
Select row in group with largest value in particular column postgres
I have a database table which looks like this. I need to group this table by id and select particular row where time_point has a largest value. Result table should look like this: Thanks for help, qwew Answer In Postgres, I would recommend distinct on to solve this top 1 per group problem: However, this does not allow possible to
Shifting the total group by 1 step- MYSQL [closed]
Closed. This question needs to be more focused. It is not currently accepting answers. Want to improve this question? Update the question so it focuses on one problem only by editing this post. Closed 2 years ago. Improve this question Here I have name and pay as columns of a database table. Table has Name and Pay(sorted lowest to highest)