Sql Server Express Localdb -

// Using DataDirectory macro (ASP.NET) "Server=(localdb)\MSSQLLocalDB;Integrated Security=true;AttachDbFileName=|DataDirectory|AppData.mdf;" using Microsoft.Data.SqlClient; string connString = @"Server=(localdb)\MSSQLLocalDB;Integrated Security=true;"; using var conn = new SqlConnection(connString); conn.Open();

❌ Production web apps, multi-user desktop apps, high concurrency, or cross-machine connections. 4. Working with LocalDB – Practical Examples 4.1 Create/Manage Instances (via SqlLocalDB.exe ) # List existing instances sqllocaldb i Create a named instance sqllocaldb create "MyInstance" Start the instance sqllocaldb start "MyInstance" Get connection string (for .\MyInstance) sqllocaldb info "MyInstance" 4.2 Connection Strings // Automatic instance (default) "Server=(localdb)\\MSSQLLocalDB;Integrated Security=true;" // Named instance with attached MDF file "Server=(localdb)\MyInstance;Integrated Security=true;AttachDbFileName=C:\Data\MyDB.mdf;" sql server express localdb

// Create a new database string sql = "CREATE DATABASE TestDB"; using var cmd = new SqlCommand(sql, conn); cmd.ExecuteNonQuery(); // Using DataDirectory macro (ASP