簡單函式從資料庫讀取並作為 DataTable 返回

這個簡單的函式將執行指定的 Select SQL 命令並將結果作為資料集返回。

Public Function ReadFromDatabase(ByVal DBConnectionString As String, ByVal SQL As String) As DataTable
    Dim dtReturn As New DataTable
    Try
        'Open the connection using the connection string
        Using conn As New SqlClient.SqlConnection(DBConnectionString)
            conn.Open()

            Using cmd As New SqlClient.SqlCommand()
                cmd.Connection = conn
                cmd.CommandText = SQL
                Dim da As New SqlClient.SqlDataAdapter(cmd)
                da.Fill(dtReturn)
            End Using
        End Using
    Catch ex As Exception
        'Handle the exception
    End Try

    'Return the result data set
    Return dtReturn
End Function

現在你可以從下面的程式碼執行上述功能

Private Sub MainFunction()
    Dim dtCustomers As New DataTable
    Dim dtEmployees As New DataTable
    Dim dtSuppliers As New DataTable

    dtCustomers = ReadFromDatabase("Server=MYDEVPC\SQLEXPRESS;Database=MyDatabase;User Id=sa;Password=pwd22;", "Select * from [Customers]")
    dtEmployees = ReadFromDatabase("Server=MYDEVPC\SQLEXPRESS;Database=MyDatabase;User Id=sa;Password=pwd22;", "Select * from [Employees]")
    dtSuppliers = ReadFromDatabase("Server=MYDEVPC\SQLEXPRESS;Database=MyDatabase;User Id=sa;Password=pwd22;", "Select * from [Suppliers]")

End Sub

上面的示例要求你的 SQL Express 例項 SQLEXPRESS 當前安裝在 MYDEVPC 上，而你的資料庫 MyDatabase 包含 Customers，Suppliers 和 Employees 表，sa 使用者密碼為 pwd22。請根據你的設定更改這些值以獲得所需的結果。