无法获取日期值

Question

我正在修改网页。网页使用的是 Visual Basic，我的数据库是 SQL 数据库。

该网页提供了病假、补休和休假的总时间。现在，我得到登录计算机的登录名，并在 tblEmployees 中查找 EmployeeID，这样我就可以通过 EmployeeID 搜索 tblTimeAvailable，然后将不同的时间相加。

我还想从 tblEmployees 获取开始日期，这样我也可以按周年日期搜索（在我从开始日期计算之后）。我在 rvsd=command2.ExecuteNonQuery 行收到错误消息“类型 'Integer' 的值无法转换为 'Date'。这是我的代码：

    Dim rve As Object
    Dim rvsd As Date
    Dim dt As Date = Today

    'Get network login name (name only)
    split = windowsLoginName.Split("\".ToCharArray)
    vname = split(1)

    'Get employeeid from table that matches login name 
    Dim Connection As String = "Data Source=WillSQL\ict2;Initial Catalog=timesql_testing;Integrated Security=SSPI"
    Using con As New SqlConnection(Connection)
        Dim sqlemp As String = "SELECT EmployeeID FROM tblEmployees where login = @loginname"
        Dim sqlstdt As String = "SELECT StartDate FROM tblEmployees where login = @loginname"
        Dim command As New SqlCommand(sqlemp, con)
        Dim command2 As New SqlCommand(sqlstdt, con)
        con.Open()
        command.Parameters.Add(New SqlParameter With {.ParameterName = "@loginname", .SqlDbType = SqlDbType.NVarChar, .Value = vname})
        command2.Parameters.Add(New SqlParameter With {.ParameterName = "@loginname", .SqlDbType = SqlDbType.NVarChar, .Value = vname})
        rve = command.ExecuteScalar
        rvsd = command2.ExecuteNonQuery
    End Using

    Dim theDateThisYear As Date

    theDateThisYear = DateSerial(Year(Now), Month(rvsd), Day(rvsd))

    If theDateThisYear < Now() Then
        theDateThisYear = DateAdd("yyyy", 1, theDateThisYear)
    End If

    Dim NextAnniversary As Date = theDateThisYear
    MsgBox(NextAnniversary)

        'Get Sick Time - DOES NOT INCLUDE CHECKING TO MAKE SURE LESS THAN ANNIV DATE YET
    Using con As New SqlConnection(Connection)
        Dim sqls1 As String = "Select SUM(NoofHours) as Total from tblTimeAvailable where workcode = 1 and EmployeeID = @emp"
        Dim command As New SqlCommand(sqls1, con)
        con.Open()
        command.Parameters.Add(New SqlParameter With {.ParameterName = "@emp", .SqlDbType = SqlDbType.NVarChar, .Value = rve})
        rvsa = command.ExecuteScalar
    End Using

在此先感谢您能给我的任何帮助！

Answer 1

假设数据库中的列 [StartDate] 的类型是 DateTime 那么您需要做的就是

rvsd = CDate(command2.ExecuteScalar)

尽管您可以通过一次查询检索到这两个值：

SELECT [EmployeeID], [StartDate] FROM [tblEmployees] where [login] = @loginname"

等等

Dim rve As String
Dim rvsd As Date

Dim connStr As String = "Data Source=WillSQL\ict2;Initial Catalog=timesql_testing;Integrated Security=SSPI"
Dim sql = "SELECT [EmployeeID], [StartDate] FROM [tblEmployees] where [login] = @loginname"

Using conn As New SqlConnection(connStr)
    Using cmd As New SqlCommand(Sql, conn)
        cmd.Parameters.Add(New SqlParameter With {.ParameterName = "@loginname", .SqlDbType = SqlDbType.NVarChar, .Value = vname})
        conn.Open()
        Dim rdr = cmd.ExecuteReader()
        If rdr.HasRows Then
            rdr.Read()
            rve = rdr.GetString(0)
            rvsd = rdr.GetDateTime(1)
        End If
    End Using
End Using

无法获取日期值

Trouble getting date value

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