Answers for "how to do subquery in sql"

why we use subquery in sql

We use subquery in order to get aggregate value in column without grouping data

what is subquery in sql

SUBQUERY IS NESTED QUERY INSIDE A SELECT, 
INSERT OR UPDATE METHODS. OR INSIDE ANOTHER SUBQUERY

subquery in sql

SELECT column_name
 FROM table_name1
WHERE VALUE IN 
(SELECT column_name
FROM table_name2 
WHERE condition)

subquery sql

UPDATE Book SET note= 'editore: ' + (SELECT name FROM Publisher WHERE Publisher.ID = Book.publisher)