In modern web applications, reporting is no longer just about displaying static data. Users expect interactive, dynamic, and drillable reports directly in their browser. ASP.NET Core, combined with SQL Server, provides a robust platform for building such reporting solutions.

This article explores how to design, implement, and optimize interactive reports in ASP.NET Core applications, with a focus on real-world best practices and scalability.

1. Understanding Interactive Reports

Interactive reports allow users to:

Unlike static reports, interactive reports require careful backend design, efficient queries, and responsive frontend interfaces.

2. Architecture Overview

A typical architecture for interactive reporting:

Browser (Angular / Razor Pages)
       |
       | HTTP/REST
       v
ASP.NET Core Web API
       |
       | SQL Queries / Stored Procedures
       v
SQL Server Database

3. Designing Reports

3.1 Identify User Requirements

3.2 Determine Data Sources

Best practice: Avoid querying multiple tables directly from frontend; centralize logic in stored procedures or backend services.

3.3 Choose Report Layout

4. Implementing Backend in ASP.NET Core

4.1 Database Access

Use Entity Framework Core or Dapper for efficient querying.

Using Dapper for performance:

using (var connection = new SqlConnection(_connectionString))
{
    var reportData = await connection.QueryAsync<ReportItem>(
        "EXEC GetSalesReport @StartDate, @EndDate",
        new { StartDate = startDate, EndDate = endDate });
    return Ok(reportData);
}

Notes

4.2 Pagination

Large reports should implement server-side pagination:

var pagedData = await connection.QueryAsync<ReportItem>(
    "EXEC GetPagedSalesReport @PageNumber, @PageSize",
    new { PageNumber = page, PageSize = pageSize });

4.3 Filtering and Sorting

Dynamic queries can be built safely using parameters:

var sql = "SELECT * FROM Sales WHERE 1=1";
if (!string.IsNullOrEmpty(region))
    sql += " AND Region = @Region";
if (!string.IsNullOrEmpty(category))
    sql += " AND Category = @Category";

var data = await connection.QueryAsync<ReportItem>(sql, new { Region = region, Category = category });

Avoid string concatenation for user input – always use parameterized queries.

4.4 Aggregation and Drill-down

Example

-- Summary
SELECT Region, SUM(SalesAmount) AS TotalSales
FROM Sales
GROUP BY Region

-- Drill-down
SELECT *
FROM Sales
WHERE Region = @SelectedRegion

5. Frontend Implementation

5.1 Choosing Framework

5.2 Data Table Libraries

Example with Angular Material Table

<table mat-table [dataSource]="dataSource" class="mat-elevation-z8">
  <ng-container matColumnDef="region">
    <th mat-header-cell *matHeaderCellDef> Region </th>
    <td mat-cell *matCellDef="let element"> {{element.region}} </td>
  </ng-container>

  <ng-container matColumnDef="totalSales">
    <th mat-header-cell *matHeaderCellDef> Total Sales </th>
    <td mat-cell *matCellDef="let element"> {{element.totalSales | currency}} </td>
  </ng-container>

  <tr mat-header-row *matHeaderRowDef="displayedColumns"></tr>
  <tr mat-row *matRowDef="let row; columns: displayedColumns;" (click)="drillDown(row)"></tr>
</table>

5.3 Charts and Visualization

Example with Chart.js

this.http.get<SalesSummary[]>('/api/reports/sales').subscribe(data => {
  this.salesChart.data.labels = data.map(d => d.region);
  this.salesChart.data.datasets[0].data = data.map(d => d.totalSales);
  this.salesChart.update();
});

5.4 Drill-down Interaction

6. Exporting Reports

Example (Excel export with EPPlus)

using var package = new ExcelPackage();
var worksheet = package.Workbook.Worksheets.Add("SalesReport");
worksheet.Cells["A1"].LoadFromCollection(reportData, true);
var excelData = package.GetAsByteArray();
return File(excelData, "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet", "SalesReport.xlsx");

7. Performance Best Practices

  1. Use indexes on filter/sort columns in SQL Server

  2. Avoid SELECT *; fetch only required columns

  3. Implement caching for frequently accessed reports

  4. Limit API response size with server-side pagination

  5. Use stored procedures or views for heavy aggregation

8. Security Considerations

9. Real-world Example: Sales Dashboard

  1. Summary Table – regional sales with drill-down to individual transactions

  2. Filter Panel – date range, category, region

  3. Charts – top-selling products, monthly trends

  4. Export Options – PDF and Excel

  5. Pagination – server-side for large datasets

  6. Role-based Access – managers see full data; staff sees limited regions

This approach is widely used in ERP systems, financial dashboards, and e-commerce analytics.

Summary

Interactive reporting in ASP.NET Core with SQL Server involves:

By following these practices, developers can deliver fast, interactive, and secure reports that scale to large datasets while maintaining a smooth user experience.