Ucef Ucef - 5 months ago 15
SQL Question

Calculate the difference between results of two count(*) queries based on 2 tables in PostgreSQL

I want to calculate the difference between the results of 2

count(*)
-type SELECT queries executed on 2 separate tables of my PostgreSQL database.

This what I'm currently using (however I should be able to wrap it all up into a single SELECT statement):

SELECT "count"(*) AS val1 FROM tab1;
SELECT "count"(*) AS val2 FROM tab2;
SELECT val2-val1;


Thanks in advance

Answer

Try this way:

select
(SELECT "count"(*) as val1 from tab1) - (SELECT "count"(*) as val2 from tab2) as total_count