How to declare a variable in PostgreSQL?

Question

I have several queries in a query window in pgAdmin, many using the same value(s). Is there a way to declare a variable, myVar to use in query statements?

SELECT * FROM table WHERE user = myVar;
INSERT INTO table(user) VALUES (myVar);

Answer 1

A simple example:

DO $$
DECLARE 
 myVar VARCHAR := myValue; 
BEGIN 
 INSERT INTO table(user) VALUES (myVar);
END $$;