不能在C＃中找到表0 ExecuteDataSet

Question

我收到例外

DataTable ProbRead = SQLData.ExecuteDataSet("SELECT description FROM chk_maintenance_probremark where subheaderid = " + lblrefno.Text.ToString() + " and Type='Problem'").Tables[0]; 

System.IndexOutOfRangeException：无法找到表0

Answer 1

看来你的SQL查询没有结果 试试这个

var probRead = SQLData.ExecuteDataSet("SELECT description FROM chk_maintenance_probremark where subheaderid = " + lblrefno.Text.ToString() + " and Type='Problem'"); 
if(probRead.Tables.Count > 0) 
{ 
    var myTable = probRead.Tables[0]; 
// do some stuff 
} 

Answer 2

查询可读：

//TODO: get rid of hardcoding, but paramterize the query 
//DONE: ToString() is redundant in lblrefno.Text 
string sql = 
    $@"select Description 
     from Chk_Maintenance_ProbRemark 
     where SubHeaderId = '{lblrefno.Text}' and 
      Type = 'Problem'"; 

，你会清楚地看到问题：lblrefno.Text.ToString()应该'包裹。

不要忘记测试，如果您有任何返回数据：

var probRead = SQLData.ExecuteDataSet(sql); 

if (probRead.Tables.Count > 0) { 
    // It's safe now to call probRead.Tables[0] 
    ... 
}