Update database.py

database.py

@@ -22,8 +22,14 @@ async def del_user(u):
         await db.execute("DELETE FROM u_tab WHERE u = ?", (u.upper().strip(),))
         await db.commit()
 
+async def check_user(u):
+    async with aiosqlite.connect(D_P) as db:
+        async with db.execute("SELECT u FROM u_tab WHERE u = ?", (u.upper().strip(),)) as cur:
+            return await cur.fetchone() is not None
+
 async def list_users():
     async with aiosqlite.connect(D_P) as db:
         async with db.execute("SELECT u FROM u_tab") as cur:
             r = await cur.fetchall()
             return [x[0] for x in r]
+