Dim sjgs As String  \' 时间格式变量
Dim bhbs As String  \' 编号标示

Dim nm As String = e.DataTable.name  \' 单据名称

Dim dr As DataRow = e.DataRow
Dim pf As String
If dr.RowState <> DataRowState.Added Then \'如果不是新增行
    Return \'那么返回
ElseIf dr.IsNull("下单日期") Then \'如果没有输入日期
    e.Cancel = True \'取消保存此行
    MessageBox.Show("必须输入下单日期!","提示",MessageBoxButtons.OK,MessageBoxIcon.Information)
    Return
Else
    Dim djb As DataTable \'SQL 查询的临时表
   
   
    Dim sj As New SQLCommand
    sj.C \'设置数据源名称
    \' sj.commandText = "Select [时间格式] From [单据编号规则]  Where 单据名称= \'" & nm & "\'"
    sj.commandText = "Select [单据名称] From [单据编号规则]"
    djb = sj.ExecuteReader()
   
    If djb.DataRows.Count > 0 Then

        sjgs = djb.DataRows(0)("时间格式")     是否写错  提示错误如图，把这个屏蔽就可以通过

         MessageBox.Show("获取成功!","提示",MessageBoxButtons.OK,MessageBoxIcon.Information)
       
    Else
        MessageBox.Show("失败!","提示",MessageBoxButtons.OK,MessageBoxIcon.Information)
       
    End If
   
End If

\'   sjgs = sj.ExecuteScalar()
\'   If sj.ExecuteScalar = 0 Then
\'     MessageBox.Show("没有时间格式!","提示",MessageBoxButtons.OK,MessageBoxIcon.Information)
\'  End If

以下是帮助的内容

pf = Format(dr("下单日期"),  sjgs )  \'我想把日期变成变量

Dim cmd2 As New SQLCommand
Dim Key As Integer
\' Dim nm As String = e.DataTable.name  \' 单据名称
cmd1.C \'设置数据源名称
cmd2.C
cmd1.commandText = "Select Count(*) From [单据编号表] Where [时间前缀] = \'" & pf & "\' And 单据名称= \'" & nm & "\'"
If cmd1.ExecuteScalar = 0 Then \'如果编号表不存在前缀的行,那么增加一行
    cmd1.commandtext = "Insert Into 单据编号表(单据名称, 时间前缀, 顺序号) Values(\'" & nm & "\',\'" & pf & "\',1)"
    cmd1.ExecuteNonQuery
End If
cmd1.commandText = "Select [顺序号] From [单据编号表] Where [时间前缀] = \'" & pf & "\' And 单据名称 = \'" & nm & "\'"
Do
    Key = cmd1.ExecuteScalar() \'从后台获得顺序号
    cmd2.commandText = "Update [单据编号表] Set [顺序号] = " & (Key + 1) & " Where [顺序号] = " & Key & " And [时间前缀] = \'" & pf & "\' And 单据名称  = \'" & nm & "\'"
    If cmd2.ExecuteNonQuery() > 0 Then \'更新顺序号
        Exit Do \'更新成功则退出循环
    End If
Loop
e.DataRow("单据编号") = bhbs & pf & "-" & Format(Key,"0000")