add backend source code

backend/app/core/database.py

@@ -0,0 +1,38 @@
+"""
+数据库连接模块
+"""
+from sqlalchemy.ext.asyncio import AsyncSession, create_async_engine, async_sessionmaker
+from sqlalchemy.orm import DeclarativeBase
+from app.core.config import settings
+
+
+# 创建异步引擎
+engine = create_async_engine(
+    settings.DATABASE_URL,
+    echo=settings.DEBUG,
+)
+
+# 创建异步会话工厂
+async_session_maker = async_sessionmaker(
+    engine,
+    class_=AsyncSession,
+    expire_on_commit=False,
+)
+
+
+class Base(DeclarativeBase):
+    """数据库模型基类"""
+    pass
+
+
+async def get_db() -> AsyncSession:
+    """获取数据库会话依赖"""
+    async with async_session_maker() as session:
+        try:
+            yield session
+            await session.commit()
+        except Exception:
+            await session.rollback()
+            raise
+        finally:
+            await session.close()