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
Return employees End Function
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.
Using connection As New SqlConnection(connectionString) Dim query As String = "SELECT EmployeeID, FirstName, LastName, Department, Salary FROM Employees" Dim adapter As New SqlDataAdapter(query, connection) Try adapter.Fill(dataTable) Catch ex As SqlException MessageBox.Show("Error: " & ex.Message) End Try End Using 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 Await connection.OpenAsync() Dim reader As SqlDataReader = Await command.ExecuteReaderAsync() While Await reader.ReadAsync() 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.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.
Return employees End Function This approach loads all data into memory and works well for data binding. Return employees End Function This approach loads all
Imports System.Data.SqlClient Public Function GetEmployeesAsDataTable() As DataTable Dim dataTable As New DataTable() Dim connectionString As String = "Server=localhost;Database=YourDatabase;Integrated Security=True;"
Return dataTable End Function For Windows Forms or WPF applications, use async methods to keep the UI responsive.
Public Shared Function GetAllEmployees() As List(Of Employee) Dim employees As New List(Of Employee)() Using conn As New SqlConnection(connectionString) Dim sql As String = "SELECT EmployeeID, FirstName, LastName, Department, Salary FROM Employees ORDER BY LastName" Using cmd As New SqlCommand(sql, conn) conn.Open() Using reader As SqlDataReader = cmd.ExecuteReader() While reader.Read() employees.Add(New Employee() With .EmployeeID = reader.GetInt32(0), .FirstName = reader.GetString(1), .LastName = reader.GetString(2), .Department = reader.GetString(3), .Salary = reader.GetDecimal(4) ) End While End Using End Using End Using Return employees End Function End Class .FirstName = reader.GetString(1)
' Database Helper Class Public Class EmployeeDB Private Shared ReadOnly connectionString As String = "Server=localhost;Database=YourDatabase;Integrated Security=True;"
Imports System.Data.SqlClient Public Function GetEmployeesWithReader() As List(Of Employee) Dim employees As New List(Of Employee)() Dim connectionString As String = "Server=localhost;Database=YourDatabase;Integrated Security=True;"
Return count End Function Always use parameters when filtering data.