feat: add sql solution to lc problem: No.2084 (#1881)

Author: thinkasany

solution/2000-2099/2084.Drop Type 1 Orders for Customers With Type 0 Orders/README.md

@@ -92,4 +92,15 @@ FROM Orders AS o
 WHERE order_type = 0 OR NOT EXISTS (SELECT 1 FROM T AS t WHERE t.customer_id = o.customer_id);
 ```
 
+```sql
+SELECT DISTINCT
+    a.order_id,
+    a.customer_id,
+    a.order_type
+FROM
+    Orders AS a
+    LEFT JOIN Orders AS b ON a.customer_id = b.customer_id AND a.order_type != b.order_type
+WHERE b.order_type IS NULL OR b.order_type = 1;
+```
+
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solution/2000-2099/2084.Drop Type 1 Orders for Customers With Type 0 Orders/README_EN.md

@@ -88,4 +88,15 @@ FROM Orders AS o
 WHERE order_type = 0 OR NOT EXISTS (SELECT 1 FROM T AS t WHERE t.customer_id = o.customer_id);
 ```
 
+```sql
+SELECT DISTINCT
+    a.order_id,
+    a.customer_id,
+    a.order_type
+FROM
+    Orders AS a
+    LEFT JOIN Orders AS b ON a.customer_id = b.customer_id AND a.order_type != b.order_type
+WHERE b.order_type IS NULL OR b.order_type = 1;
+```
+
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