[sql] How to use SQL Select statement with IF EXISTS sub query?

How to select Boolean value from sub query with IF EXISTS statement (SQL Server)?

It should be something like :

SELECT 
  TABEL1.Id, 
  NewFiled = (IF EXISTS(SELECT Id FROM TABLE2 WHERE TABLE2.ID = TABEL1.ID) 
                 SELECT 'TRUE' 
              ELSE 
                 SELECT 'FALSE') 
FROM TABEL1

Use a CASE statement and do it like this:

SELECT 
    T1.Id [Id]
    ,CASE WHEN T2.Id IS NOT NULL THEN 'TRUE' ELSE 'FALSE' END [Has Foreign Key in T2]
FROM
    TABLE1 [T1]
    LEFT OUTER JOIN
        TABLE2 [T2]
        ON
        T2.Id = T1.Id

You can also use ISNULL and a select statement to get this result

SELECT
Table1.ID,
ISNULL((SELECT 'TRUE' FROM TABLE2 WHERE TABLE2.ID = TABEL1.ID),'FALSE') AS columName,
etc
FROM TABLE1

SELECT Id, 'TRUE' AS NewFiled FROM TABEL1
INTERSECT
SELECT Id, 'TRUE' AS NewFiled FROM TABEL2
UNION
SELECT Id, 'FALSE' AS NewFiled FROM TABEL1
EXCEPT
SELECT Id, 'FALSE' AS NewFiled FROM TABEL2;