简单函数从数据库读取并作为 DataTable 返回

这个简单的函数将执行指定的 Select SQL 命令并将结果作为数据集返回。

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

现在你可以从下面的代码执行上述功能

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 实例 SQLEXPRESS 当前安装在 MYDEVPC 上，而你的数据库 MyDatabase 包含 Customers，Suppliers 和 Employees 表，sa 用户密码为 pwd22。请根据你的设置更改这些值以获得所需的结果。