Question

我有一个数据库，我在其中创建了一个表＆＃34; CampWheelDenominationno＆＃34;，我有一个特定的行＆＃34; quota＆＃34;
我需要选择＆＃34; slno＆＃34;相应的＆＃34;配额＆＃34;什么时候＆＃34;配额＆＃34; 变为零。

我的SQL代码是

"select slno from CampWheelDenomination where quota_allowded = 0"

现在我需要添加这些＆＃34; slno＆＃34;到列表..我已经做了一个我自己的方法但是没有用

public int checkCodeinDb()
{


    using (IDbConnection dbConnection = new SqliteConnection (connectionString))
    {
        dbConnection.Open ();
        using (IDbCommand dbCmd = dbConnection.CreateCommand ())
        {
            string sqlQuery = "select slno from CampWheelDenomination where quota_allowded = 0";
            dbCmd.CommandText = sqlQuery;
            using (IDataReader reader = dbCmd.ExecuteReader ())
            {
                while (reader.Read ()) 
                {
                    //slnolist is a list i have created at begining
                SlNoList.Add (reader.GetString (0));
                }

                return slnolist ; //error at here

            foreach (string st in SlNoList)// i have done this to check whether the slno is added to the list.
            {
                print (st);
            }


                dbConnection.Close ();
                reader.Close ();
            }
        }
    }
}

如何将这些slno从数据库添加到SlNOList

错误是无法隐式转换类型System.Collections.Generic.List<string>' to int＆＃39;在行返回时发生SlNoList

Answer 1

您正在尝试返回List但功能返回类型为int。按如下方式更改功能定义：

public List<string> checkCodeinDb()
{ 
///your usual code here

另外看一下你的代码，你可能应该在你的函数中有一个List并返回它。

示例：

List<string> slnolist = checkCodeinDb();

public List<string> checkCodeinDb()
{
List<string> data;
///your usual code here and add your database returned value to data variable and finally return it
return data;
}

Answer 2

并且还要将数据库中的值添加到列表中，我们可以使用此代码

public void checkCodeinDb()
{


        using (IDbConnection dbConnection = new SqliteConnection (connectionString))
        {
            dbConnection.Open ();
            using (IDbCommand dbCmd = dbConnection.CreateCommand ())
            {
                string sqlQuery = "select slno from CampWheelDenomination where quota_allowded = 0";
                dbCmd.CommandText = sqlQuery;
                using (IDataReader reader = dbCmd.ExecuteReader ())
                {
                    while (reader.Read ()) 
                    {




                    string ad = reader ["slno"].ToString();

                    SlNoList.Add (ad);

                    }






                foreach (string st in SlNoList)
                {
                    print (st);
                }     





                    dbConnection.Close ();
                    reader.Close ();


                }
            }
        }
    }

如何将数据库中的值添加到统一列表中

2 个答案: