How to use SQL Select statement with IF EXISTS sub query?
Use CASE:
SELECT TABEL1.Id, CASE WHEN EXISTS (SELECT Id FROM TABLE2 WHERE TABLE2.ID = TABLE1.ID) THEN 'TRUE' ELSE 'FALSE' END AS NewFiled FROM TABLE1If TABLE2.ID is Unique or a Primary Key, you could also use this:
SELECT TABEL1.Id, CASE WHEN TABLE2.ID IS NOT NULL THEN 'TRUE' ELSE 'FALSE' END AS NewFiled FROM TABLE1 LEFT JOIN Table2 ON TABLE2.ID = TABLE1.ID
You can also use ISNULL and a select statement to get this result
SELECTTable1.ID,ISNULL((SELECT 'TRUE' FROM TABLE2 WHERE TABLE2.ID = TABEL1.ID),'FALSE') AS columName,etcFROM TABLE1
SELECT Id, 'TRUE' AS NewFiled FROM TABEL1INTERSECTSELECT Id, 'TRUE' AS NewFiled FROM TABEL2UNIONSELECT Id, 'FALSE' AS NewFiled FROM TABEL1EXCEPTSELECT Id, 'FALSE' AS NewFiled FROM TABEL2;