feat:更新数据表结构

service/subject_service.py

@@ -0,0 +1,13 @@
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from models.library import Subject
+
+
+async def get_subject_by_name(db: AsyncSession, subject: str) -> int:
+    stmt = select(Subject).where(Subject.name == subject)
+    subject = (await db.execute(stmt)).scalar_one_or_none()
+    if not subject:
+        raise ValueError("Subject not found")
+
+    return subject.id