如何从vb.net查询中返回多个值

一个问题是如何将多个查询结果值存储或返回到多个变量中。。我使用的查询返回4列，但如何。。单独将这些结果存储到4个单独的变量中。。这是我的密码

私有子FrmAlumnos_LoadByVal发送方作为System.Object，ByVal e作为System.EventArgs处理MyBase.Load txtCurrentUser.Text=Login.txtexser.Text

    Dim strsql As String
    strsql = "SELECT ""Agregar"", ""Modificar"", ""Eliminar"", ""Imprimir"" FROM ""Seguridad"".""GrupoPantallas"" WHERE ""IdGrupo"" = (SELECT ""IdGrupo"" FROM ""Seguridad"".""Users"" WHERE ""IdUsers"" = '" _
        + Me.txtCurrentUser.Text + "') AND ""IdPantalla"" = '" + Me.Name + "'"
    Try
        Using conexion As New Devart.Data.PostgreSql.PgSqlConnection(My.Settings.CNX_Principal)
            Dim comando As New Devart.Data.PostgreSql.PgSqlCommand(strsql, conexion)
            conexion.Open()
            Dim registro As Devart.Data.PostgreSql.PgSqlDataReader = comando.ExecuteReader
            If comando.ExecuteReader.Item(0) = 0 Then
                btnNew.Visible = False
            End If
            If comando.ExecuteReader.Item(1) = 0 Then
                btnEdit.Visible = False
            End If
            If comando.ExecuteReader.Item(2) = 0 Then
                btnDelete.Visible = False
            End If
            If comando.ExecuteReader.Item(3) = 0 Then
                btnPrint.Visible = False
            End If
        End Using

    Catch ex As Exception

    End Try
End Sub

---

我使用PostgreSQL只是为了让您知道…

我想您可能会发现这里有一个有用的数据集。比如：

Dim ds As New DataSet
Dim com As New SqlCommand
com.Connection = <yourconnectionstring>
com.CommandType = CommandType.Text
com.CommandText = "YOURSQLSTUFF"
Dim da As New DataAdapter
da.SelectCommand = com

da.Fill(ds)
ds.Tables(0).TableName = "FirstTable"
ds.Tables(0).PrimaryKey = New DataColumn() {ds.Tables(0).Columns("primaryKeyOfFirstTable")
ds.Tables(1).TableName = "SecondTable"
ds.Tables(1).PrimaryKey = New DataColumn() {ds.Tables(1).Columns("primaryKeyOfSecondTable")

希望有帮助

-科幻小说

编辑：经过更多的搜索，我找到了链接，这可能会帮助你！这是postgreSQL特有的

Dim strsql As String
strsql = "SELECT ""Agregar"", ""Modificar"", ""Eliminar"", ""Imprimir"" FROM ""Seguridad"".""GrupoPantallas"" WHERE ""IdGrupo"" = (SELECT ""IdGrupo"" FROM ""Seguridad"".""Users"" WHERE ""IdUsers"" = '" _
    + Me.txtCurrentUser.Text + "') AND ""IdPantalla"" = '" + Me.Name + "'"
Try
    Using conexion As New Devart.Data.PostgreSql.PgSqlConnection(My.Settings.CNX_Principal)
        Dim comando As New Devart.Data.PostgreSql.PgSqlCommand(strsql, conexion)
        conexion.Open()
        Dim registro As Devart.Data.PostgreSql.PgSqlDataReader = comando.ExecuteReader
        //This is the loop that you missed
        While registro.Read()
            If comando.ExecuteReader.Item(0) = 0 Then
                btnNew.Visible = False
            End If
            If comando.ExecuteReader.Item(1) = 0 Then
                btnEdit.Visible = False
            End If
            If comando.ExecuteReader.Item(2) = 0 Then
                btnDelete.Visible = False
            End If
            If comando.ExecuteReader.Item(3) = 0 Then
                btnPrint.Visible = False
            End If
        End While
    End Using

Catch ex As Exception

End Try

---

我不确定您是否正在尝试这样做，但您所要做的就是如上所示在DataReader中循环。

您需要使用DataReader的读取方法：

Dim strsql As String
strsql = "SELECT ""Agregar"", ""Modificar"", ""Eliminar"", ""Imprimir"" FROM ""Seguridad"".""GrupoPantallas"" WHERE ""IdGrupo"" = (SELECT ""IdGrupo"" FROM ""Seguridad"".""Users"" WHERE ""IdUsers"" = '" _
    + Me.txtCurrentUser.Text + "') AND ""IdPantalla"" = '" + Me.Name + "'"
Try
    Using conexion As New Devart.Data.PostgreSql.PgSqlConnection(My.Settings.CNX_Principal)
        Dim comando As New Devart.Data.PostgreSql.PgSqlCommand(strsql, conexion)
        conexion.Open()
        Using registro As Devart.Data.PostgreSql.PgSqlDataReader = comando.ExecuteReader()
            //Assuming that there is only a single row returned
            If registro.Read()
                btnNew.Visible = registro.GetBoolean(0)
                btnEdit.Visible = registro.GetBoolean(1)
                btnDelete.Visible = registro.GetBoolean(2)
                btnPrint.Visible = registro.GetBoolean(3)
            End While
        End Using
    End Using
Catch ex As Exception

End Try

---

您还应该研究如何使用参数。这将使代码比使用串联字符串更简洁，并将阻止sql注入攻击。

为什么不进行4次查询？是的，我知道我有4次查询，每次查询一次，但是否有一种方法可以在一次查询中完成？reply1查询的thnx=1对象。因此，如果您只需要一个查询，您可以创建一个对象，然后将该对象拆分为4个新对象。ExecuteReader返回一个数据读取器。但是我如何比较第一个元素、第二个元素和第三个元素……如果postgreSQL不支持这种语法，那么我想它不会有多大用处。也许这会引导你做类似的事情！但是当调用ExecuteReader方法时，仍然向数据库发送4个查询！是的，你说得对。我的意思是将comando.ExecuteReader.Item0=0的行更改为registro0=0或您要查找的任何字段。基本上…一旦运行ExecuteReader，只需使用reader对象寄存器，而不是在运行之后调用ExecuteReader 4次。希望这是有意义的。当然，我的假设是你返回了不止一张记录。