Why should you care?

Filtering TenantId then OrderDate matches how multi-tenant apps query — put the equality column first.

See it live — copy this example

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

USE DataVerse;
IF COL_LENGTH('dbo.Orders', 'OrderDate') IS NULL
    ALTER TABLE dbo.Orders ADD OrderDate DATE NOT NULL CONSTRAINT DF_Orders_OrderDate DEFAULT (CAST(SYSUTCDATETIME() AS DATE));
CREATE NONCLUSTERED INDEX IX_Orders_City_OrderDate
ON dbo.Orders (City, OrderDate)
INCLUDE (Amount);
SELECT OrderId, Amount
FROM dbo.Orders
WHERE City = N'Mumbai' AND OrderDate >= '2026-01-01';

What happened?

• Key order City then OrderDate supports equality on City plus range on OrderDate.
• INCLUDE keeps Amount covered.

Practice next

1. Create the composite index.
2. Run the Mumbai date-range query and check for Seek.
3. Filter only OrderDate and see a less ideal plan.
4. Query WHERE City = N'Pune' only — still uses left prefix.
5. Add OrderId to INCLUDE for full covering.

Remember

Multi-column keys are ordered. Equality columns usually lead. Design indexes from real WHERE clauses.

City operations queue

Warehouse app lists DataVerse orders for a city by date.

Outcome: Composite index matches the screen filter exactly.