Mysql constant field error occurred when doing related query [Err] 1064 - You have an error in your SQL syntax;

Question

I use this sql to do query testing :

select '1101' as login_id,
a.project_id,a.user_id
from table1 as a on login_id = a.user_id

But the error message is:

[Err] 1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'on login_id = a.user_id' at line 3

The data in table1 likes this:

id	project_id	user_id
1	A001	1002
2	A002	1001
3	A001	1001
4	A004	1003
5	A005	1004

Answer 1

on is for table joining, in this case I think you want to do something like this :

select '1101' as login_id,
a.project_id,a.user_id
from table1 as a 
where a.user_id = '1101'

---

for the expect output you can use case :

select '1001' as login_id,
case when user_id = '1001' then project_id else null end as project_id,
case when user_id = '1001' then user_id else null end as user_id
from table1

here is the db<>fiddle.

just saw the parameter part, just add a parameter which replace 1001 in the syntax and I think the result will be good. although I think keeping all those null data is a weird choose.