I am using a MySQL database with the following related tables:
Transaction->Purchase->Item->Schedule
Transaction - holds details about transactions.
Purchase - keeps track of purchase details such as quantity when multiple items are bought. Each Transaction may include several Purchase_IDs.
Item - stores details about the items and associates them with specific clients.
Schedule - determines the price of an item at various times of the day.
I need to write a query that retrieves values from the Schedule table based on whether Transaction.TimeStamp is within a specified date range. This query needs to access a value from Schedule using its primary key, but I cannot trace this key back through the Transaction table.
To solve this, I am considering creating a linking table to connect Transaction directly to the primary key of Schedule.
I’ve recently learned about views in databases, and I’m uncertain if this is a suitable scenario for creating a view instead of building an actual table named TransactionSchedule.
transactionSchedule
Transaction_ID Schedule_ID
I am unclear about the situations in which a view is advantageous or what benefits it provides.
Is it excessive to create a separate table just to link Transaction to Schedule? Any insights would be appreciated.
NOTE: This query is meant solely for retrieving pre-existing data.
Based on your description, I think you’re overcomplicating this. You already have a clear relationship path: Transaction→Purchase→Item→Schedule. There’s no need for an additional linking table or view if you can trace the foreign keys through your existing structure.
A simple JOIN across all four tables should work perfectly for your query. Something like SELECT * FROM Transaction t JOIN Purchase p ON t.id = p.transaction_id JOIN Item i ON p.item_id = i.id JOIN Schedule s ON i.schedule_id = s.id WHERE t.TimeStamp BETWEEN 'start_date' AND 'end_date'.
Views are useful when you frequently run complex queries and want to simplify them, but they don’t solve relationship problems. A physical linking table would only make sense if you genuinely need a many-to-many relationship between Transaction and Schedule, which doesn’t seem to be your case here. The performance impact of JOINing through your existing relationships should be minimal with proper indexing on your foreign key columns.
The decision between a view and physical table depends heavily on your data access patterns and performance characteristics. Since you mentioned this is read-only, I would lean toward neither option initially and focus on optimizing your existing join path.
However, if performance becomes an issue with the four-table join, a view would be more appropriate than a physical linking table. The reason is that your Transaction-to-Schedule relationship isn’t truly many-to-many - it’s a derived relationship through your existing foreign key chain. Creating a physical TransactionSchedule table would essentially be denormalizing your data, which introduces consistency risks.
A view encapsulates the join logic and provides a cleaner query interface without the overhead of maintaining redundant data. You can always add appropriate indexes on the underlying tables to improve join performance. The view approach also keeps your schema normalized while giving you the query simplification you’re looking for.
Start with optimizing the direct joins first, then consider a view if the query complexity becomes unwieldy.
Creating a dedicated TransactionSchedule table might actually be worth considering depending on your query frequency and performance requirements. While the existing relationship chain works theoretically, joining four tables repeatedly can become expensive with larger datasets, especially if you’re running this type of query frequently.
I’ve worked with similar database structures where we initially relied on multi-table joins but eventually moved to materialized linking tables for performance reasons. The key question is whether you’re dealing with high-volume data or frequent queries that would benefit from pre-computed relationships.
If you decide against the physical table, consider creating an indexed view instead of a regular view. MySQL supports indexed views which can provide better performance than standard views while avoiding the maintenance overhead of a separate table. However, keep in mind that indexed views have their own update costs.
The deciding factor should be your query patterns and data volume rather than avoiding complexity for its own sake.
honestly sounds like you dont even need either option tbh. why not just use the existing foreign key chain with proper joins? creating extra tables or views seems overkill when transaction->purchase->item->schedule already gives you the path. just index your foreign keys properly and the query should run fine without adding complexity to your schema.
Views would be the better choice here rather than creating another physical table. Since you mentioned this is purely for data retrieval, a view eliminates the overhead of maintaining additional storage and keeping duplicate data synchronized.
I’ve dealt with similar scenarios where creating unnecessary linking tables became a maintenance nightmare. Every time the underlying data changed, we had to ensure the linking table stayed current. Views automatically reflect changes in the base tables without any extra effort.
Create a view that encapsulates your JOIN logic from Transaction through Purchase, Item, to Schedule. This gives you a clean interface for your queries while preserving the existing relational structure. The view will handle the foreign key traversal internally, and you can filter on TimeStamp directly.
Physical linking tables make sense for true many-to-many relationships, but your case appears to be following a natural hierarchical path. Adding TransactionSchedule would introduce redundancy and potential data integrity issues. Views perform well for read operations and will simplify your query logic significantly.