Update README.md

Learner457 · web-flow · commit 504e0bdb9d95 · 2025-05-21T18:29:15.000+05:30
diff --git a/README.md b/README.md
@@ -60,10 +60,20 @@ ON s.product_id = p.product_id
 
 [1581 - Customer Who Visited but Did Not Make Any Transactions](https://leetcode.com/problems/customer-who-visited-but-did-not-make-any-transactions/)
 ```sql
-SELECT customer_id, COUNT(*) as count_no_trans
-FROM Visits 
-WHERE visit_id NOT IN (SELECT DISTINCT visit_id FROM Transactions)
-GROUP BY customer_id
+select v.customer_id, count(v.visit_id) as count_no_trans
+from Visits v
+left join Transactions t
+On v.visit_id = t.visit_id
+Where t.transaction_id is Null
+group by v.customer_id;
+
+--2nd approach: using Subquery (This approach is not ideal as this problem can be solved using joins)
+SELECT customer_id, COUNT(visit_id) as count_no_trans 
+FROM Visits
+WHERE visit_id NOT IN (
+	SELECT visit_id FROM Transactions
+	)
+GROUP BY customer_id;
 ```
 
 [197 - Rising Temperature](https://leetcode.com/problems/rising-temperature/) 
