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Check value of last 4 rows

I want to check the value of the last 4 rows from DB. If these 4 rows have a specific value, Do something. So the table looks like this: Here is a fiddle to test with: http://sqlfiddle.com/#!9/1064b3/1 I can run the following query SELECT * FROM testing ORDER BY id DESC LIMIT 4, Then check with PHP: Is there …

Using one query’s result into another

I have this query which shows the below result, I want to use this MarksObtained and take out min, max and avg of each course and show it with the second query (have provided below). This is the second query So it will basically show min, max and avg of each course achieved by the students. What I want: Sampl…

SQL Error 3780 when using foreign key as primary key

I’m getting the following order trying to use a table’s primary key as another table’s primary key: ERROR 3780 (HY000): Referencing column ‘optimization_id’ and referenced column ‘optimization_id’ in foreign key constraint ‘optimization.main – optimization…

Adding time to a table in SQLplus without date

I am trying to create a table regarding telecommunication and I want to add time for 2 rows call_start_time and call_end_time and with that, I want to calculate the call_duration. This is what I used to enter the value If I use this format while displaying the data only the date is displayed not the time. Can…

I can not convert the data to the required form

Hi hi I have a Nodejs server and I am using PostgreSQL, the bottom part of my database. How can I select data and represent it like this (in one sql query): I wrote a request but it is far from what I need: Answer You can use a cte to first build the question JSON data, and then aggregate

Postgres query return nothing where there should be a valid data

I have a query that should return some rows, but it returns blank. As far as I know .. the pictures down will show the issue. Here is the query This is the table : I tested the calculation and it worked a lone . Answer Your condition cannot be right because you are comparing M.PLAYED_AT to be BETWEEN M.PLAYED…