Create postgresql.sql

Author: Deepak-Vohra

sql-queries-12/updating-rows-subquery-referencing-same-table/postgresql.sql

@@ -0,0 +1,13 @@
+-- Self-join
+UPDATE Program AS P1
+SET end_date = P2.start_date + INTERVAL '3 weeks'
+FROM Program AS P2
+WHERE P1.id = p2.id;
+
+-- Subquery within UPDATE ... SET
+UPDATE Program
+SET end_date = (
+    SELECT start_date + INTERVAL '3 weeks'
+    FROM Program AS Temp
+    WHERE Temp.id = Program.id
+);