switch device

BD_4s/task_from_lection.sql

@@ -0,0 +1,25 @@
+
+INSERT INTO A VALUES
+(1,2),
+(2,3);
+
+INSERT INTO B VALUES
+(1,1),
+(2,3);
+
+INSERT INTO C VALUES
+(1,2,1,1),
+(1,2,2,2),
+(2,3,1,1),
+(1,2,4,5);
+
+
+SELECT a.F1, a.F2 FROM a,b,c
+WHERE a.F1 = c.F1 AND a.F2 = c.F2 AND b.F3 = c.F3 AND b.F4 = c.F4
+GROUP BY a.F1, a.F2 HAVING COUNT (a.F1) = (SELECT COUNT(F3) FROM b);
+
+SELECT F1, F2 FROM C
+    WHERE F3 IN (SELECT F3 FROM B) AND F4 IN (SELECT F4 FROM B)
+    GROUP BY F1, F2 HAVING COUNT(*) = (
+        SELECT COUNT(*) FROM b
+    );