fix sql query

app.py

@@ -151,14 +151,18 @@ async def get_logs(
         params.append(model)
 
     if start:
-        query += " AND timestamp >= ?"
+        if not query.endswith("WHERE"):
+            query += " AND"
+        query += " timestamp >= ?"
         params.append(start)
 
     if end:
-        query += " AND timestamp <= ?"
+        if not query.endswith("WHERE"):
+            query += " AND"
+        query += " timestamp <= ?"
         params.append(end)
 
-    query += " ORDER BY timestamp DESC LIMIT 100"
+    query += " ORDER BY timestamp DESC LIMIT 500"
 
     print(query, params)