Why should you care?

Ops boards need fresh numbers without freezing checkout.

See it live — copy this example

Run in SQL Server Management Studio (SSMS) or Azure Data Studio.

USE DataVerse;
SELECT COUNT(*) AS OpenOrders, SUM(Amount) AS OpenValue
FROM dbo.Orders
WHERE Status = 'Open';
-- Better at scale: maintain a summary table updated in the same tran as status changes
IF OBJECT_ID(N'dbo.OrderStatusSummary', N'U') IS NOT NULL DROP TABLE dbo.OrderStatusSummary;
CREATE TABLE dbo.OrderStatusSummary (
    Status VARCHAR(10) NOT NULL PRIMARY KEY,
    OrderCount INT NOT NULL,
    TotalAmount DECIMAL(18,2) NOT NULL
);

What happened?

• The live COUNT works for small labs.
• OrderStatusSummary sketches a maintained aggregate for dashboards under load — update it when status changes.

Practice next

1. Run the live open-orders query.
2. Create OrderStatusSummary.
3. Design a trigger or proc path to maintain it.
4. Index filtered on Status = 'Open'.
5. Compare query cost vs reading OrderStatusSummary.

Remember

Fresh ≠ full scan forever. Summaries/replicas protect OLTP. Pick freshness vs cost deliberately.

Ops wallboard

Warehouse screens show open order counts from DataVerse summaries.

Outcome: Board stays live; checkout latency unchanged.