Imports Npgsql
Public Class Form1

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        '' 確保連線關閉後重新打開連接
        'conn.Close()
        'If conn.State = ConnectionState.Closed Then
        '    conn.ConnectionString = ConString
        '    conn.Open()
        'End If

        '' SQL 查詢範例
        'Dim SQL1 As String = "SELECT datname FROM pg_database"
        '' 放入 DataGridView 範例
        'Dim ds1 As New DataSet
        'cmd.Connection = conn
        'cmd.CommandText = SQL1
        'da.SelectCommand = cmd
        'da.Fill(ds1)
        '月清單_DGV.DataSource = ds1.Tables(0)
        'conn.Close()

        ' 確保連線關閉後重新打開連接
        conn.Close()
        If conn.State = ConnectionState.Closed Then
            conn.ConnectionString = ConString
            conn.Open()
        End If

        ' SQL 查詢範例
        Dim SQL1 As String = "SELECT * FROM public.hr_employee"

        ' 放入 DataGridView 範例
        Dim ds1 As New DataSet
        cmd.Connection = conn
        cmd.CommandText = SQL1
        da.SelectCommand = cmd
        da.Fill(ds1)
        月清單_DGV.DataSource = ds1.Tables(0)
        conn.Close()

        '' 單純取出字串的範例
        'cmd.CommandText = SQL1
        'cmd.Connection = conn
        'dr = cmd.ExecuteReader()
        'If dr.Read() Then
        '    Dim 資料庫版本 As String = dr("系統認證版本號").ToString()
        '    Dim 版本號 As String = dr("系統認證版本號").ToString()
        'End If
        'conn.Close()
    End Sub
End Class