diff --git a/examples/basic.py b/examples/basic.py
index aa8f005..157f2dc 100644
--- a/examples/basic.py
+++ b/examples/basic.py
@@ -20,6 +20,24 @@
         machine_id=generate_machine_id_from_key("myMachineKeyIdentifier"),
         context=[{"key": "scenario-version", "value": "1.0.0"}],
         message="test message to see where it is written",
+        decisions=[
+            {
+                "origin": "crowdsec",
+                "duration": "1h",
+                "scenario": "crowdsec/ssh-bf",
+                "scope": "ip",
+                "type": "ban",
+                "value": "81.81.81.81",
+            },
+            {
+                "origin": "pysdk",
+                "duration": "2h",
+                "scenario": "crowdsec/ssh-bf",
+                "scope": "ip",
+                "type": "ban",
+                "value": "81.81.81.81",
+            },
+        ],
     )
 ]
 
diff --git a/src/cscapi/sql_storage.py b/src/cscapi/sql_storage.py
index 66e662d..4bbf47d 100644
--- a/src/cscapi/sql_storage.py
+++ b/src/cscapi/sql_storage.py
@@ -1,5 +1,5 @@
 from dataclasses import asdict
-from typing import List
+from typing import List, Optional
 
 from dacite import from_dict
 from sqlalchemy import (
@@ -12,6 +12,7 @@
     create_engine,
     delete,
     update,
+    event,
 )
 from sqlalchemy.orm import (
     DeclarativeBase,
@@ -21,9 +22,23 @@
     sessionmaker,
 )
 
+from sqlalchemy.engine import Engine
 from cscapi import storage
 
 
+"""
+By default, foreign key constraints are disabled in SQLite.
+@see https://docs.sqlalchemy.org/en/20/dialects/sqlite.html#foreign-key-support
+"""
+
+
+@event.listens_for(Engine, "connect")
+def set_sqlite_pragma(dbapi_connection, connection_record):
+    cursor = dbapi_connection.cursor()
+    cursor.execute("PRAGMA foreign_keys=ON")
+    cursor.close()
+
+
 class Base(DeclarativeBase):
     def to_dict(self):
         return {c.name: getattr(self, c.name) for c in self.__table__.columns}
@@ -33,7 +48,7 @@ class MachineDBModel(Base):
     __tablename__ = "machine_models"
 
     id = Column(Integer, primary_key=True, autoincrement=True)
-    machine_id = Column(TEXT)
+    machine_id = Column(TEXT, unique=True)
     token = Column(TEXT)
     password = Column(TEXT)
     scenarios = Column(TEXT)
@@ -54,7 +69,7 @@ class DecisionDBModel(Base):
     type = Column(TEXT)
     value = Column(TEXT)
     signal_id: Mapped[int] = mapped_column(
-        "signal_id", ForeignKey("signal_models.alert_id")
+        "signal_id", ForeignKey("signal_models.alert_id", ondelete="CASCADE")
     )
 
 
@@ -71,6 +86,9 @@ class SourceDBModel(Base):
     value = Column(TEXT)
     as_name = Column(TEXT)
     longitude = Column(Float)
+    signal_id = Column(
+        Integer, ForeignKey("signal_models.alert_id", ondelete="CASCADE")
+    )
 
 
 class ContextDBModel(Base):
@@ -80,7 +98,7 @@ class ContextDBModel(Base):
     value = Column(TEXT)
     key = Column(TEXT)
     signal_id: Mapped[int] = mapped_column(
-        "signal_id", ForeignKey("signal_models.alert_id")
+        "signal_id", ForeignKey("signal_models.alert_id", ondelete="CASCADE")
     )
 
 
@@ -100,8 +118,6 @@ class SignalDBModel(Base):
     stop_at = Column(TEXT, nullable=True)
     sent = Column(Boolean, default=False)
 
-    source_id = Column(Integer, ForeignKey("source_models.id"), nullable=True)
-
     context: Mapped[List["ContextDBModel"]] = relationship(
         "ContextDBModel", backref="signal"
     )
@@ -133,29 +149,29 @@ def get_all_signals(self) -> List[storage.SignalModel]:
             for res in self.session.query(SignalDBModel).all()
         ]
 
-    def get_machine_by_id(self, machine_id: str) -> storage.MachineModel:
-        exisiting = (
+    def get_machine_by_id(self, machine_id: str) -> Optional[storage.MachineModel]:
+        existing = (
             self.session.query(MachineDBModel)
             .filter(MachineDBModel.machine_id == machine_id)
             .first()
         )
-        if not exisiting:
-            return
+        if not existing:
+            return None
         return storage.MachineModel(
-            machine_id=exisiting.machine_id,
-            token=exisiting.token,
-            password=exisiting.password,
-            scenarios=exisiting.scenarios,
-            is_failing=exisiting.is_failing,
+            machine_id=existing.machine_id,
+            token=existing.token,
+            password=existing.password,
+            scenarios=existing.scenarios,
+            is_failing=existing.is_failing,
         )
 
     def update_or_create_machine(self, machine: storage.MachineModel) -> bool:
-        exisiting = (
+        existing = (
             self.session.query(MachineDBModel)
             .filter(MachineDBModel.machine_id == machine.machine_id)
             .all()
         )
-        if not exisiting:
+        if not existing:
             self.session.add(MachineDBModel(**asdict(machine)))
             self.session.commit()
             return True
@@ -193,19 +209,19 @@ def update_or_create_signal(self, signal: storage.SignalModel) -> bool:
                 for dec in signal.decisions
             ]
 
-        exisiting = (
+        existing = (
             self.session.query(SignalDBModel)
             .filter(SignalDBModel.alert_id == signal.alert_id)
             .first()
         )
 
-        if not exisiting:
+        if not existing:
             self.session.add(to_insert)
             self.session.commit()
             return True
 
         for c in to_insert.__table__.columns:
-            setattr(exisiting, c.name, getattr(to_insert, c.name))
+            setattr(existing, c.name, getattr(to_insert, c.name))
 
         self.session.commit()
         return False
@@ -215,9 +231,11 @@ def delete_signals(self, signals: List[storage.SignalModel]):
             SignalDBModel.alert_id.in_((signal.alert_id for signal in signals))
         )
         self.session.execute(stmt)
+        self.session.commit()
 
     def delete_machines(self, machines: List[storage.MachineModel]):
         stmt = delete(MachineDBModel).where(
-            MachineDBModel.machine_id in ([machine.machine_id for machine in machines])
+            MachineDBModel.machine_id.in_((machine.machine_id for machine in machines))
         )
         self.session.execute(stmt)
+        self.session.commit()