diff --git a/.gitignore b/.gitignore
index cc0f159..cdea58f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,3 @@
 .venv
 /.idea/
-/database.db
+/api/database.db
diff --git a/api/.env b/api/.env
new file mode 100644
index 0000000..f631b6c
--- /dev/null
+++ b/api/.env
@@ -0,0 +1,2 @@
+SQLITE_FILE_NAME=database2.db
+DATABASE_URL=sqlite:///database2.db
\ No newline at end of file
diff --git a/api/main.py b/api/main.py
index a3db2db..39ad509 100644
--- a/api/main.py
+++ b/api/main.py
@@ -1,28 +1,35 @@
 import datetime
 
 from fastapi import FastAPI
+from sqlalchemy.exc import IntegrityError
 from sqlmodel import Session, SQLModel, create_engine, select
 from contextlib import asynccontextmanager
-
 from api.models import Car, FuelItem
+from pydantic_settings import BaseSettings, SettingsConfigDict
 
-sqlite_file_name = "database.db"
-sqlite_url = f"sqlite:///{sqlite_file_name}"
+
+class Settings(BaseSettings):
+    database_url: str = ""
+    sqlite_file_name: str = ""
+
+    model_config = SettingsConfigDict(env_file=".env")
+
+
+settings = Settings()
+
+database_url = settings.database_url
 
 connect_args = {
         "check_same_thread": False
         }
-engine = create_engine(sqlite_url, echo=True, connect_args=connect_args)
+engine = create_engine(database_url, echo=True, connect_args=connect_args)
 
 
 def create_db_and_tables():
     SQLModel.metadata.create_all(engine)
 
 
-@asynccontextmanager
-async def lifespan(app: FastAPI):
-    # startup
-    create_db_and_tables()
+def fill_database():
     car = Car(id_string="Auto 1")
     with Session(engine) as session:
         session.add(car)
@@ -37,6 +44,16 @@ async def lifespan(app: FastAPI):
         session.add(fill_item)
         session.commit()
         session.refresh(fill_item)
+
+
+@asynccontextmanager
+async def lifespan(app: FastAPI):
+    # startup
+    create_db_and_tables()
+    try:
+        fill_database()
+    except IntegrityError as e:
+        print(e)
     yield
 
 
diff --git a/api/models.py b/api/models.py
index ec7a845..d790d40 100644
--- a/api/models.py
+++ b/api/models.py
@@ -5,12 +5,12 @@ from sqlmodel import Field, SQLModel
 
 class Car(SQLModel, table=True):
     id: int | None = Field(default=None, primary_key=True)
-    id_string: str = Field(nullable=False, index=True)
+    id_string: str = Field(nullable=False, index=True, unique=True)
 
 
 class FuelItem(SQLModel, table=True):
     id: int | None = Field(default=None, primary_key=True)
-    car_id: int | None = Field(default=None, foreign_key="car.id")
-    date: datetime.date = Field(nullable=False, index=True)
+    car_id: int | None = Field(default=None, foreign_key="car.id", unique_items=True)
+    date: datetime.date = Field(nullable=False, index=True, unique_items=True)
     odometer_reading: float = Field(nullable=False)
     fuel_fill: float = Field(nullable=False)
diff --git a/requirements.txt b/api/requirements.txt
similarity index 83%
rename from requirements.txt
rename to api/requirements.txt
index bfd1b84..167566b 100644
--- a/requirements.txt
+++ b/api/requirements.txt
@@ -7,7 +7,8 @@ uvicorn==0.38.0
 idna==3.11
 pydantic==2.12.*
 pydantic_core==2.41.*
+pydantic_settings==2.11.*
 sniffio==1.3.*
-starlette==0.48.*
+starlette==0.49.*
 typing-inspection==0.4.*
 typing_extensions==4.15.*