SQL Subquery column equals operation - sql

Question

I am trying to do a SQL query for user with certain permission enabled flag. I know, I can do this:
select u.ID, u.Name,
(select p.Value
from Permissions p
where p.UserID = u.ID AND p.Key = 'CanEdit') as IsPermissionEnabled
from Users u
But it's not exactly what I need, can I do something like this:
select u.ID, u.Name,
((select p.Value
from Permissions p
where p.UserID = u.ID AND p.Key = 'CanEdit') = 'True')
as IsPermissionEnabled
from Users u
It didn't work for me. So, how to change my query to make it work?

Answer 1

Surely you should just join to the table to get p.Value.
Then you can do with it whatever you like:
SELECT
u.ID,
u.Name,
p.Value as IsPermissionEnabled
FROM Users u
LEFT OUTER JOIN Permissions p
ON p.UserID = u.ID
AND p.Key = 'CanEdit';

Answer 2

Try this query
select u.ID, u.Name, case when p.value>0 then 'True' else '' end
as IsPermissionEnabled
from Users u
left join permission p on p.UserID = u.ID and p.key='CanEdit'

Answer 3

In SQL Server, you need an explicit case statement. So, you can write the query as:
select u.ID, u.Name,
(case when (select p.Value
from Permissions p
where p.UserID = u.ID AND p.Key = 'CanEdit'
) = 'True'
then 1 else 0
end) as IsPermissionEnabled
from Users u;

Answer 4

A join ( inner or left) with a Case can be used to return the desired data with IsPermissionEnabled. Assuming intent is to treat IsPermissionEnabled as boolean, the case statement can set it to a bit value of 0 or 1 as below.
select u.USERID , u.Username, IsPermissionEnabled = case p.[Key] when 'CanEdit' then 1 else 0 end from [Permissions] p inner join [User] u on u.USERID = p.userid