Create README.md

elinabel · web-flow · commit 2d762272dc9b · 2024-08-22T16:00:14.000+03:00
diff --git a/Урок 10.2 Представления/README.md b/Урок 10.2 Представления/README.md
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+# Представления
+```sql
+create view film_amount as 
+select
+	f.film_id,
+	sum(p.amount) as amount
+from
+	film f
+left join inventory i 
+on
+	i.film_id = f.film_id
+left join rental r 
+on
+	r.inventory_id = i.inventory_id
+left join payment p 
+on
+	p.rental_id = r.rental_id
+group by
+	f.film_id;
+```
+```sql
+explain
+select
+	*
+from
+	film_amount;
+```
+```sql
+explain
+select
+	f.film_id,
+	sum(p.amount) as amount
+from
+	film f
+left join inventory i 
+on
+	i.film_id = f.film_id
+left join rental r 
+on
+	r.inventory_id = i.inventory_id
+left join payment p 
+on
+	p.rental_id = r.rental_id
+group by
+	f.film_id;
+```
+```sql
+create materialized view film_amount_mat as 
+select
+	f.film_id,
+	sum(p.amount) as amount
+from
+	film f
+left join inventory i 
+on
+	i.film_id = f.film_id
+left join rental r 
+on
+	r.inventory_id = i.inventory_id
+left join payment p 
+on
+	p.rental_id = r.rental_id
+group by
+	f.film_id;
+```
+```sql
+explain
+select
+	*
+from
+	film_amount_mat;
+```
+```sql
+explain
+select
+	f1.*
+from
+	film_amount f1
+join film_amount f2
+on
+	f1.film_id = f2.film_id;
+```
+```sql
+explain
+select
+	f1.*
+from
+	film_amount_mat f1
+join film_amount_mat f2
+on
+	f1.film_id = f2.film_id;
+```
+```sql
+refresh materialized view film_amount_mat;
+```
