MySQL 查询适用于 Workbench，但不适用于 C# 代码

Question

SQL 查询：

SELECT som.id, som.name, som.search_enabled, oc.id, oc.name
FROM option_category oc
INNER JOIN skill_option so
    on oc.id=so.option_category_id
INNER JOIN skill_option_master som
    on som.id=so.id;

在 Workbench 中工作正常：

但是，在我的 C# 代码中：

List<string> listItems = getMultiColumnListFromDB(

                         "SELECT som.id, som.name, som.search_enabled, oc.id, oc.name " +
                         "FROM option_category oc " +
                         "INNER JOIN skill_option so " +
                         "   on oc.id=so.option_category_id " +
                         "INNER JOIN skill_option_master som "  +
                         "   on som.id=so.id; "

                         ,new string[] { "som.id", "som.name", "som.search_enabled", "oc.id", "oc.name" });

...

private List<string> getMultiColumnListFromDB(string query, string[] columnNames)
    {
        List<string> result = new List<string>();

        MySqlConnection con = new MySqlConnection(dbConnectionString);
        MySqlCommand cmd = new MySqlCommand(query, con);

        con.Open();

        MySqlDataReader reader = cmd.ExecuteReader();

        while (reader.Read())
        {
            string strResult = "";
            foreach (string columnName in columnNames)
            {
                if (reader[columnName] == DBNull.Value) 
                    //If value is NULL, we assume yes/1
                    strResult = strResult + "1" + ";";
                else
                    strResult = strResult + reader[columnName].ToString() + ";";

            }
            result.Add(strResult.TrimEnd(';'));
        }
        return result;
    }

...我得到：System.IndexOutOfRangeException: 'Could not find specified column in results: som.id' at Line: if (reader[columnName] == DBNull.Value )

作为测试，我在调试回 Workbench 时从异常窗口复制了查询，它无需任何修改即可工作1。更简单的查询（没有连接）在我的应用程序中工作正常。我很欣赏我的代码不是最优雅的，但我无法克服上面的1。怎么可能？

谢谢

Answer 1

修改 SQL 查询为列名起别名：

SELECT som.id as 'som.id', som.name as 'som.name', som.search_enabled as 'som.search_enabled', oc.id as 'oc.id', oc.name as 'oc.name'
FROM option_category oc
INNER JOIN skill_option so
   on oc.id=so.option_category_id
INNER JOIN skill_option_master som
   on som.id=so.id;