Substitute 2 IDs by Name in SQL - mysql

Question

I have 2 tables that looks like the below:
Table 1
Table 2
What Im trying to do, is I want to substitute the change_builder ID from table 1 by the first and last name from table 2. In addition, I want to do the same for the change_manager_ID in table 2 (Substitute it by the first and last name from table 2)
My query looks like the below:
SELECT a.change_number, a.title, change_manager_id,change_builder_id, concat(users.first_name,' ', users.last_name) as Manager_Name, concat(users.first_name,' ', users.last_name) as Builder_Name,
(CASE
WHEN a.change_state_id = '128' THEN 'In Progress'
WHEN a.change_state_id = '127' THEN 'Approved'
WHEN a.change_state_id = '125' THEN 'Pending'
WHEN a.change_state_id = '124' THEN 'Requested'
END) AS Change_State
FROM change_item as a
LEFT JOIN users
ON a.change_manager_id = users.id
WHERE a.change_state_id = 128
OR a.change_state_id = 124
OR a.change_state_id = 125
OR a.change_state_id = 127
The output of this is changing the first and last name of the manager w.r.t the ID but I want to do the same for the builder as well.
I'm stuck, any help or hint would be really appreciated.

Answer 1

Seems you have forgotten that you can join a table twice to the same other table - each join depicting a different relationship.
Good practice requires you to give each join clause a good correlation name to describe the role of the relationship.
And, please, use the right literals for the right types.
Not once change_state_id = '128' (string) and then change_state_id = 124 (number). Implicit conversions are slow and can impact the data quality.
And I used an IN () clause instead of a bunch of OR-s:
SELECT
a.change_number
,a.title
,change_manager_id
,change_builder_id
,CONCAT (mgr.first_name,' ',mgr.last_name) AS Manager_Name
,CONCAT (bld.first_name,' ',bld.last_name) AS Builder_Name
,CASE
WHEN a.change_state_id = 128 THEN 'In Progress'
WHEN a.change_state_id = 127 THEN 'Approved'
WHEN a.change_state_id = 125 THEN 'Pending'
WHEN a.change_state_id = 124 THEN 'Requested'
END AS Change_State
FROM change_item AS a
LEFT JOIN users AS mgr -- join as manager
ON a.change_manager_id = mgr.id
LEFT JOIN users AS bld -- join as builder
ON a.change_builder_id = bld.id
WHERE a.change_state_id IN(128,124,125,127)
;