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Tag: sql

Count rows after joining three tables in PostgreSQL

Suppose I have three tables in PostgreSQL: Suppose I am using the using the following query: I get 50 as count. Whereas with: I get only 25 as count. What is my mistake in the second query? What can I do to get the same count? My requirement is that there is a single user table, referenced by multiple tables.

How to calculate power consumption from power records?

I have table which contains power values (kW) for devices. Values are read from each device once a minute and inserted into table with timestamp. What I need to do is calculate power consumption (kWh) for given time span and return 10 most power consuming devices. Right now I query results for given time span…

SELECT if 2 cells in a row are equal

Tried to show it as simple as possible. I want to SELECT Subject if 2 cells in a row are equal Table Result I need is to select subject C cause username and lastpostername are equal (Sorted DESC by ID, so newest comes first) Answer

@SET (SQL) in PHP

How to state SET @unix_four_weeks_ago = UNIX_TIMESTAMP(curdate()) – 2419200; in php file. SQL PHP The query is all about getting the last 4weeks records. The query was working fine in SQL, but not giving any output when I run php file. Answer As the others already said, multi_query will allow you to run…