Rohes SQL, Stored Procedures und Interpolation

Wann Sie Raw SQL in EF Core verwenden sollten

Sichere parametrisierte Abfragen mit FromSqlRaw

// SAFE: parameterized
var products = await _db.Products
    .FromSqlRaw("SELECT * FROM Products WHERE Price > {0}", 100m)
    .ToListAsync();

// DANGEROUS: never do this
// FromSqlRaw("SELECT * FROM Products WHERE Price > " + price)

Sicherheit durch interpolierte Zeichenfolgen mit FromSqlInterpolated

decimal minPrice = 100m;
string category = "Electronics";

var products = await _db.Products
    .FromSqlInterpolated(
        $"SELECT * FROM Products WHERE Price > {minPrice} AND Category = {category}")
    .OrderBy(p => p.Name)
    .ToListAsync();
// Values become @p0, @p1 parameters automatically

LINQ nach FromSql zusammenstellen

decimal min = 50m;
var page = await _db.Products
    .FromSqlInterpolated($"SELECT * FROM Products WHERE Price > {min}")
    .Where(p => p.IsActive)        // additional LINQ filter
    .OrderBy(p => p.Price)
    .Skip(0).Take(20)              // pagination
    .ToListAsync();
// Generates: SELECT ... FROM (raw SQL) AS p WHERE ...

Gespeicherte Prozeduren ausführen

// Stored proc returning Products
var products = await _db.Products
    .FromSqlRaw("EXEC GetProductsByCategory {0}", "Books")
    .ToListAsync();

// Stored proc with no return rows
await _db.Database.ExecuteSqlRawAsync(
    "EXEC ArchiveOldOrders {0}",
    DateTime.UtcNow.AddYears(-1));

ExecuteSqlInterpolated für DML

int days = 30;
int affected = await _db.Database.ExecuteSqlInterpolatedAsync(
    $"UPDATE Orders SET Status = 'Expired' WHERE PlacedAt < {DateTime.UtcNow.AddDays(-days)}");

Console.WriteLine($"{affected} orders expired");

Nicht-Entitätstypen abfragen

// Query a DTO directly — no entity needed
var stats = await _db.Database
    .SqlQuery<ProductStats>(
        $"SELECT Category, COUNT(*) AS Count, AVG(Price) AS AvgPrice FROM Products GROUP BY Category")
    .ToListAsync();

public record ProductStats(string Category, int Count, decimal AvgPrice);

Schlüssellose Entitätstypen für Views

public class ProductSalesSummary
{
    public string Category { get; set; } = "";
    public int TotalSold { get; set; }
    public decimal Revenue { get; set; }
}

// In OnModelCreating:
modelBuilder.Entity<ProductSalesSummary>()
    .HasNoKey()
    .ToView("vw_ProductSalesSummary");

// Query:
var summary = await _db.Set<ProductSalesSummary>().ToListAsync();

Fallstricke bei SQL-Injection vermeiden

// SAFE
var name = userInput;
var result = await _db.Products
    .FromSqlInterpolated($"SELECT * FROM Products WHERE Name = {name}")
    .ToListAsync();

// INJECTION RISK (never do this)
// FromSqlRaw("SELECT * FROM Products WHERE Name = '" + name + "'");

Ausgabeparameter mit ADO.NET-Fallback

await _db.Database.OpenConnectionAsync();
var conn = _db.Database.GetDbConnection();
using var cmd = conn.CreateCommand();
cmd.CommandText = "EXEC GetOrderCount @CustomerId, @Count OUTPUT";
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.Add(new SqlParameter("@CustomerId", 5));
var outParam = new SqlParameter("@Count", SqlDbType.Int) { Direction = ParameterDirection.Output };
cmd.Parameters.Add(outParam);
await cmd.ExecuteNonQueryAsync();
int count = (int)outParam.Value;

Praxisbeispiel: Fallback für die Volltextsuche

string query = "keyboard mechanical";
var results = await _db.Products
    .FromSqlInterpolated(
        $"SELECT * FROM Products WHERE FREETEXT(Name, {query})")
    .AsNoTracking()
    .Take(20)
    .ToListAsync();

Kurzer Check

Zusammenfassung: Raw SQL in EF Core