Question

我在MySql Db中有一个名为newtbl的表，其中有2列作为外键引用，它们是m_id，p_id。我希望显示这些名称而不是这些m_id和p_id。

我写的查询在下面，但是有错误。

public void Main()
        {
            // TODO: Add your code here
            string filename;//= Dts.Variables["User::filename"].Value.ToString();
            filename = @"D:\VersionWithDummyData\finbalReviewTest.xlsm";
            string S_Directory = @"D:\VersionWithDummyData\";
            if (S_Directory.Substring(S_Directory.Length - 1, 1) != @"\")
            {
               S_Directory = S_Directory + @"\";
            }

            DirectoryInfo finfo = new DirectoryInfo(S_Directory);

            if (filename.ToString().Substring(1, 2) != "~$")
            {
                try
                {
                    xls.Application ExcelObj = new xls.Application();
                    ExcelObj.DisplayAlerts = true;
                    ExcelObj.Visible = true;
                    ExcelObj.DefaultFilePath = S_Directory;

                    xls.Workbook eBook = ExcelObj.Workbooks.Open(filename.ToString(), false, false,
                        Type.Missing, "", "", true, xls.XlPlatform.xlWindows, "",
                        false, false, 0, false, true, 0);

                    foreach (xls.WorkbookConnection wc in eBook.Connections)
                    {
                        if (wc.Type.ToString() == "xlConnectionTypeODBC")
                        {
                            wc.ODBCConnection.BackgroundQuery = false;
                        }
                        else
                        {
                            wc.OLEDBConnection.BackgroundQuery = false;
                        }
                    }

                    eBook.RefreshAll();
                    eBook.Save();
                    ExcelObj.Run("Module1",Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing
                        , Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing
                        , Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing
                        , Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing
                        , Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing
                        , Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing);
                    eBook.Save();
                    ExcelObj.Workbooks.Close();
                    ExcelObj.Quit();
                }
                catch (COMException e)
                {
                    MessageBox.Show(filename.ToString() + " has an issue with error " + e.Message);
                }
            }

            Dts.TaskResult = (int)ScriptResults.Success;
        }

Answer 1

您可以尝试使用as

列别名

select newtbl.*, pa.p_name, m.m_id  as 'mmID'
from newtbl 
left join matches m on newtbl.m_id = m.m_id 
left join players pa on newtbl.p_id = pa.p_id

Answer 2

下面是我的问题的答案。

 select newtbl.u_id, pa.p_name from newtbl left join players pa on newtbl.p_id = pa.p_id

在MySQL中检索列名而不是外部ID

2 个答案: