check if shipmaster is already on the water

src/model/user.rs

@@ -93,6 +93,17 @@ WHERE name like ?
         .ok()
     }
 
+    pub async fn on_water(&self, db: &SqlitePool) -> bool {
+        sqlx::query!(
+            "SELECT * FROM logbook WHERE shipmaster=? AND arrival is null",
+            self.id
+        )
+        .fetch_optional(db)
+        .await
+        .unwrap()
+        .is_some()
+    }
+
     pub async fn all(db: &SqlitePool) -> Vec<Self> {
         sqlx::query_as!(
             User,