Question

代码在很长一段时间内都运行良好，直到有人在SQL数据库中添加新名称（SE01）导致Web程序崩溃。网页错误显示

System.InvalidCastException: Conversion from string "SE01" to type 'Integer'
is not valid.

以及其他SQL Union查询错误，

SELECT Substring([Name],@lenSrv, 8) as Name 
FROM [dbo].[ServerOwners] 
where [Name] like @Srv 
and Name not like '%j%' 
union 
SELECT Substring([Server],@lenSrv, 8) as Name 
FROM [dbo].[AuditLog] 
where log='delete' 
and [DATE] > (GETDATE() - 60) 
and [SERVER] like @Srv 
and Server not like '%j%' 
order by [name]

代码作业是使用查询通过数据库查找下一个可用名称，例如，数据库中存在的servername是UXVP001，代码将找到免费的UXVP002。现在有人在SQL数据库中添加了UXVPSE01，这似乎导致读取查询崩溃。我希望它被接受/忽略新名称而不会出错。

以下是搜索数据库的剪切的vb代码，

srv = "UXPV"
sqlAddOn =  "and Name not like '%j%'"
sqlAddOnAudit = "and Server not like '%j%'"

        "Logic to find next available name"
        "1. select the numbers to the right of the characters"
        "2.  loop all values and find first missing number"
        Dim sqlConn As New System.Data.SqlClient.SqlConnection((ConfigurationManager.ConnectionStrings("SOCT").ConnectionString))
        Dim strSql As String = "SELECT  Substring([Name],@lenSrv, 8) as Name  FROM [dbo].[ServerOwners] where [Name] like @Srv " & sqlAddOn
        strSql &= " union "
        strSql &= "SELECT  Substring([Server],@lenSrv, 8) as Name FROM [dbo].[AuditLog] where log='delete' and [DATE] > (GETDATE() - 60) and [SERVER] like @Srv " & sqlAddOnAudit
        strSql &= " order by [name]"
        Dim cmd As New System.Data.SqlClient.SqlCommand(strSql, sqlConn)
        Dim dr As System.Data.SqlClient.SqlDataReader

        LabelError.Text = ""
        Dim x As Integer = 1
        Dim y As Integer = 1
        Dim foundYet As Boolean = False
        Try
            sqlConn.Open()
            cmd.Parameters.AddWithValue("@lenSrv", srv.Length + 1)
            cmd.Parameters.AddWithValue("@Srv", srv & "%")

            dr = cmd.ExecuteReader()

            While dr.Read() And foundYet = False
            LabelError.Text = LabelError.Text & dr("Name") & " | "
            y = CType(dr("Name"), Integer)
            If x = y Then
                "keep going"
                x = x + 1
            Else
                "you found first available number"
                foundYet = True
            End If
        End While

        dr.Close()
        cmd.Dispose()
    Catch ex As Exception
        hide()
        PanelError.Visible = True
        LabelError.Text = ex.ToString() & "<hr/>" & strSql
    Finally
        sqlConn.Dispose()

    End Try

    "make sure leading zeros are present"
    " 000"
    Dim fmt As String = "00#"
    tbAdd_ServerName.Text = srv & x.ToString(fmt)
    tbAdd_ServerName.Enabled = False

    tbAdd_TM.SelectedValue = "*"

Answer 1

当然这不起作用。您正在将UXPV右侧的所有内容都拿走，然后将该值视为数字。但是，对于一条记录，您不再拥有该值的数字。

因此，您需要做的是摆脱不良记录并更改用户界面，以便将来无法添加数据类型。或者您需要修复代码以删除所有字母字符。

Answer 2

我意识到我所要做的就是添加忽略“SE”，就像这样，

sqlAddOn = "and Name not like '%j%' and Name not like '%se%'"
sqlAddOnAudit = "and Server not like '%j%' and Server not like '%se%'"

现在它正在工作并回到它想象的方式进行搜索。

SQL联合查询错误与vb.net

2 个答案: