Public Function GetEmployeesByDepartment(deptName As String) As DataTable Dim dataTable As New DataTable() Dim connectionString As String = "Server=localhost;Database=YourDatabase;Integrated Security=True;" Using connection As New SqlConnection(connectionString) Dim query As String = "SELECT EmployeeID, FirstName, LastName, Salary FROM Employees WHERE Department = @Department" Dim command As New SqlCommand(query, connection) ' Add parameter to prevent SQL injection command.Parameters.AddWithValue("@Department", deptName) Dim adapter As New SqlDataAdapter(command) Try adapter.Fill(dataTable) Catch ex As SqlException MessageBox.Show("Error: " & ex.Message) End Try End Using
CREATE TABLE Employees ( EmployeeID INT PRIMARY KEY IDENTITY(1,1), FirstName NVARCHAR(50), LastName NVARCHAR(50), Department NVARCHAR(50), Salary DECIMAL(10,2) ); SqlDataReader provides the fastest read performance for large result sets but is read-only and forward-only. vb.net code to retrieve data from sql server
' Employee class definition Public Class Employee Public Property EmployeeID As Integer Public Property FirstName As String Public Property LastName As String Public Property Department As String Public Property Salary As Decimal Public ReadOnly Property FullName As String Get Return $"FirstName LastName" End Get End Property End Class DataAdapter for flexibility
Imports System.Configuration Dim connectionString As String = ConfigurationManager.ConnectionStrings("DefaultConnection").ConnectionString You now have multiple reliable methods to retrieve data from SQL Server using VB.NET. Choose the approach based on your specific needs: SqlDataReader for performance, DataAdapter for flexibility, and async methods for responsive UI applications. vb.net code to retrieve data from sql server
Using connection As New SqlConnection(connectionString) Dim query As String = "SELECT EmployeeID, FirstName, LastName, Department, Salary FROM Employees" Dim command As New SqlCommand(query, connection) Try connection.Open() Dim reader As SqlDataReader = command.ExecuteReader() While reader.Read() Dim emp As New Employee() emp.EmployeeID = Convert.ToInt32(reader("EmployeeID")) emp.FirstName = reader("FirstName").ToString() emp.LastName = reader("LastName").ToString() emp.Department = reader("Department").ToString() emp.Salary = Convert.ToDecimal(reader("Salary")) employees.Add(emp) End While reader.Close() Catch ex As SqlException MessageBox.Show("SQL Error: " & ex.Message) End Try End Using
Imports System.Data.SqlClient Public Async Function GetEmployeesAsync() As Task(Of List(Of Employee)) Dim employees As New List(Of Employee)() Dim connectionString As String = "Server=localhost;Database=YourDatabase;Integrated Security=True;"