vues

banque.functions.md

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+# Fonctions
+
+```sql
+insert into exchange_rate values
+  ('EUR', '1999-01-04', 1),
+  ('USD', '1999-01-04', 1.1789),
+  ('YEN', '1999-01-04', 133.73);
+```
+
+```sql
+create or replace function latest_exchange_rate (
+  p_code text,
+  p_date date
+)
+returns decimal
+language sql
+as $$
+select rate
+  from exchange_rate
+  where currency_code = p_code
+    and date < p_date
+    order by date desc
+    limit 1;
+$$;
+```