Add Compute The md5 Hash Of A String as a postgres til

postgres/compute-the-md5-hash-of-a-string.md

@@ -0,0 +1,22 @@
+# Compute The md5 Hash Of A String
+
+One of the functions provided by PostgreSQL for working with string data is
+the `md5()` function. This function calculates the md5 hash of a given string.
+
+It works like this:
+
+```sql
+> select md5('Hello, World!');
+               md5
+----------------------------------
+ 65a8e27d8879283831b664bd8b7f0ad4
+
+> select md5('$3cr3tp4$$w0rd');
+               md5
+----------------------------------
+ bbabecfd4031211077473734bae7249f
+```
+
+There are more hashing algorithms provided by the `pgcrypto` extension. See
+[Compute Hashes With pgcrypto](postgres/compute-hashes-with-pgcrypto.md) for
+more details on that.