Question

我想使数据字段成为变量，我按如下方式编写了代码。 SQL有效，但是当我尝试获取返回值时，如果我删除+，则返回+ StrVariable +，然后按字面值返回Strvariable。

Private Function FUNCTStrSN(StrVariable As String, StrSN As String) As String
    Dim sqlConn As SqlConnection
    Dim sqlComm As SqlCommand
    Dim r As SqlDataReader
    Dim sqlstring As String

    sqlstring = "Select " + StrVariable + "  FROM HistorySNUnit WHERE SN='" + StrSN + "'"
    sqlConn = New SqlConnection(DBConnection) : sqlConn.Open() : sqlComm = New SqlCommand(sqlstring, sqlConn) : r = sqlComm.ExecuteReader()
    While r.Read()
        Dim DBSN As String = CStr(r("StrVariable"))
        StrSN = DBSN
    End While : r.Close() : sqlConn.Close()
    FUNCTStrSN = StrSN
End Function

如何正确检索值？谢谢！

Answer 1

尝试使用参数创建SQL Command

Private Function FUNCTStrSN(StrVariable As String, StrSN As String) As String
     Dim sqlConn As SqlConnection
     Dim sqlComm As SqlCommand
     Dim r As SqlDataReader
     Dim sqlstring As String

     sqlstring = "Select @variable FROM HistorySNUnit WHERE SN=@value"
     sqlConn = New SqlConnection(DBConnection) : sqlConn.Open() : sqlComm = New SqlCommand(sqlstring, sqlConn)
     sqlComm.Parameters.AddWithValue("@variable", StrVariable)
     sqlComm.Parameters.AddWithValue("@value", StrSN)
     r = sqlComm.ExecuteReader()
     While r.Read()
         Dim DBSN As String = CStr(r(StrVariable))
         StrSN = DBSN
     End While : r.Close() : sqlConn.Close()
     FUNCTStrSN = StrSN
End Function

ExecuteReader，使字段变量

1 个答案: