prevent unauthorized access to administrative db0 when connection to redis-cli

README.md

@@ -47,18 +47,24 @@ HeroDB can be interacted with using any standard Redis client, such as `redis-cl
 
 ### Example with `redis-cli`
 
+Connections start with no database selected. You must SELECT a database first.
+
+- To work in the admin database (DB 0), authenticate with the admin secret:
 ```bash
+redis-cli -p 6379 SELECT 0 KEY myadminsecret
 redis-cli -p 6379 SET mykey "Hello from HeroDB!"
 redis-cli -p 6379 GET mykey
 # → "Hello from HeroDB!"
+```
 
+- To use a user database, first create one via the JSON-RPC API (see docs/rpc_examples.md), then select it:
+```bash
+# Suppose RPC created database id 1
+redis-cli -p 6379 SELECT 1
 redis-cli -p 6379 HSET user:1 name "Alice" age "30"
 redis-cli -p 6379 HGET user:1 name
 # → "Alice"
-
 redis-cli -p 6379 SCAN 0 MATCH user:* COUNT 10
-# → 1) "0"
-#    2) 1) "user:1"
 ```
 
 ## Cryptography