demo, MySQL - rextester

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#MySQL 5.7.12
#please drop objects you've created at the end of the script 
#or check for their existance before creating
#'\\' is a delimiter

DROP TABLE IF EXISTS items_revenue;
CREATE TABLE items_revenue (id int, is_manager int, manager_id int, name varchar(55), no_of_items int, revenue int);
INSERT INTO items_revenue (id, is_manager, manager_id, name, no_of_items, revenue)
VALUES
    (1  ,    1     ,    0     , 'Manager1' ,    621    ,   833), 
    (2  ,    1     ,    0     , 'Manager2' ,    458    ,   627),
    (3  ,    1     ,    0     , 'Manager3' ,    872    ,   1027 ),
    (8  ,    0     ,    1     , 'Member1'  ,    1258   ,   1582),
    (9  ,    0     ,    2     , 'Member2'  ,    5340   ,   8827),
    (10  ,    0     ,    3     , 'Member3'  ,    3259   ,   5124);

SELECT
    CASE WHEN manager_id = 0 THEN id ELSE manager_id END AS manager_id,
    MAX(CASE WHEN is_manager=1 THEN name END) AS name,
    SUM(no_of_items) AS total_items,
    SUM(revenue) AS total_revenue
FROM items_revenue
GROUP BY
    CASE WHEN manager_id = 0 THEN id ELSE manager_id END;


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