sql: Implement bot state

Allows for persistent, dynamic storage of configuration options outside
of the config.json file.

The bot_state table is, essentially, a key-value store for config
options. There are two new prepared statements, `state` and
`update_state`:

- `state` will return the value for the provided key
- `update_state` will create the key or update an existing key

2 files changed, 7 insertions, 0 deletions

diff --git a/migrations/0002-state.sql b/migrations/0002-state.sql
new file mode 100644
index 0000000..2465d30
--- /dev/null
+++ b/migrations/0002-state.sql
@@ -0,0 +1,5 @@
+CREATE TABLE IF NOT EXISTS bot_state (
+    id SERIAL PRIMARY KEY,
+    setting TEXT NOT NULL,
+    value TEXT NOT NULL
+);
\ No newline at end of file
diff --git a/migrations/0003-unique-state-key.sql b/migrations/0003-unique-state-key.sql
new file mode 100644
index 0000000..1d19219
--- /dev/null
+++ b/migrations/0003-unique-state-key.sql
@@ -0,0 +1,2 @@
+ALTER TABLE bot_state DROP CONSTRAINT IF EXISTS setting_unique;
+ALTER TABLE bot_state ADD CONSTRAINT setting_unique UNIQUE (setting);
\ No newline at end of file