diff --git a/src/commands/users.rs b/src/commands/users.rs
index da968f6..f552787 100644
--- a/src/commands/users.rs
+++ b/src/commands/users.rs
@@ -10,17 +10,26 @@ pub async fn register(
     email: String,
 ) -> Result<(), Error> {
     if let Some(guild_id) = ctx.guild_id() {
-        let new_user = NewUser {
-            discord_id: ctx.author().id.0 as i64,
-            guild_id: guild_id.into(),
-            first_name,
-            last_name,
-            email,
-        };
+        let discord_id = ctx.author().id.0 as i64;
 
         {
             let mut conn = ctx.data().pool.get()?;
-            new_user.insert(&mut conn);
+
+            if User::get(&mut conn, guild_id.into(), discord_id)?.is_some() {
+                ctx.say("You've already been registered.").await?;
+
+                return Ok(());
+            }
+
+            let new_user = NewUser {
+                discord_id,
+                guild_id: guild_id.into(),
+                first_name,
+                last_name,
+                email,
+            };
+
+            new_user.insert(&mut conn)?;
         }
 
         ctx.say("You have been registered.").await?;
diff --git a/src/db/mod.rs b/src/db/mod.rs
index 1542bea..578506e 100644
--- a/src/db/mod.rs
+++ b/src/db/mod.rs
@@ -34,10 +34,7 @@ fn initialize_db(conn: &mut SqliteConnection) -> Result<(), DbError> {
 pub fn initialize_pool(url: &str) -> Result<Pool<ConnectionManager<SqliteConnection>>, DbError> {
     let manager = ConnectionManager::new(url);
 
-    let pool = Pool::builder()
-        .test_on_check_out(true)
-        .build(manager)
-        .expect("oops");
+    let pool = Pool::builder().test_on_check_out(true).build(manager)?;
 
     let mut conn = pool.get()?;
     initialize_db(&mut conn)?;
diff --git a/src/db/users.rs b/src/db/users.rs
index 09360ee..e87f0b9 100644
--- a/src/db/users.rs
+++ b/src/db/users.rs
@@ -1,14 +1,12 @@
 use super::schema::users::{self, dsl::*};
 use diesel::dsl::Eq;
 use diesel::dsl::{AsSelect, Select};
-use diesel::expression::AsExpression;
 use diesel::helper_types::Filter;
 use diesel::prelude::*;
-use diesel::sql_types::BigInt;
 use diesel::sqlite::Sqlite;
 use diesel::sqlite::SqliteConnection;
 
-#[derive(Queryable, Selectable)]
+#[derive(Queryable, Selectable, AsChangeset)]
 #[diesel(table_name = users)]
 pub struct User {
     pub id: i32,
@@ -52,23 +50,30 @@ impl User {
         conn: &mut SqliteConnection,
         guild_id_: i64,
         discord_id_: i64,
-    ) -> Result<User, diesel::result::Error> {
+    ) -> Result<Option<User>, diesel::result::Error> {
         Self::all()
             .filter(guild_id.eq(guild_id_))
             .filter(discord_id.eq(discord_id_))
             .first(conn)
+            .optional()
     }
 
-    pub fn get_by_id(conn: &mut SqliteConnection, id_: i32) -> Result<User, diesel::result::Error> {
-        Self::all().filter(id.eq(id_)).first(conn)
+    pub fn get_by_id(
+        conn: &mut SqliteConnection,
+        id_: i32,
+    ) -> Result<Option<User>, diesel::result::Error> {
+        Self::all().find(id_).first(conn).optional()
+    }
+
+    pub fn update(&self, conn: &mut SqliteConnection) -> Result<usize, diesel::result::Error> {
+        diesel::update(users::table).set(self).execute(conn)
     }
 }
 
 impl NewUser {
-    pub fn insert(&self, conn: &mut SqliteConnection) -> User {
+    pub fn insert(&self, conn: &mut SqliteConnection) -> Result<User, diesel::result::Error> {
         diesel::insert_into(users::table)
             .values(self)
             .get_result(conn)
-            .expect("fuck")
     }
 }
diff --git a/src/main.rs b/src/main.rs
index c1457cf..6328584 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -84,7 +84,7 @@ async fn main() {
         ..Default::default()
     };
 
-    let pool = db::initialize_pool("affy.db").unwrap();
+    let pool = db::initialize_pool("affy.db").expect("Failed to initialize database.");
 
     poise::Framework::builder()
         .token(