试图通过最近与ID SCOPE_IDENTITY，它的错误我：指定的转换是无效 [英] Trying to pass recent ID with scope_identity, and its error me : Specified cast is not valid

问题描述

我试着通过最近的ID，我只是用SCOPE_IDENTITY插入，
和它给我一些奇怪的东西。
它说：

Im trying to pass the recent ID that I just insert with Scope_Identity, and its giving me some weird stuff. it says :

：指定的转换是无效的。

: Specified cast is not valid

和指的是该行：

int IdOfRecentHistoryGame = (Int32)commandquery.ExecuteScalar();

这是code的其余部分：

this is the rest of the code :

string username = Session["Session"].ToString();

            con = new SqlConnection("Data Source=MICROSOF-58B8A5\\SQL_SERVER_R2;Initial Catalog=Daniel;Integrated Security=True");
            con.Open();

            string knowWhichOne = "SELECT ID FROM Users WHERE Username='" + UserOrGuest.Text + "'";

            SqlCommand comm = new SqlCommand(knowWhichOne, con);
            int userID = (Int32)comm.ExecuteScalar();

            knowWhichOne = "SELECT ClassID FROM Users WHERE Username='" + UserOrGuest.Text + "'";

            comm = new SqlCommand(knowWhichOne, con);
            int classID = (Int32)comm.ExecuteScalar();

            knowWhichOne = "SELECT SchoolID FROM Users WHERE Username='"+UserOrGuest.Text + "'";

            comm = new SqlCommand(knowWhichOne, con);
            int schoolID = (Int32)comm.ExecuteScalar();

            if (RadioWords.Checked == true)
            {
                 game = 1;
            }
            else
            {
                 game = 2;
            }
            string arr = "";
            for (int i = 0; i < ListBox.Items.Count; i++)
            {
                arr += ListBox.Items[i] +",";
            }

            string sqlqueryString = "INSERT INTO HistoryOfGames (GameID, UserID, LengthOfArray, NumberOfErrors, ClassID, SchoolID,Arrayarray) VALUES (@GameID, @UserID, @LengthOfArray, @NumberOfErrors, @ClassID, @SchoolID, @Arrayarray);" + "SELECT SCOPE_IDENTITY()";

            SqlCommand commandquery = new SqlCommand(sqlqueryString, con);

            commandquery.Parameters.AddWithValue("GameID", game);
            commandquery.Parameters.AddWithValue("UserID", userID);
            commandquery.Parameters.AddWithValue("LengthOfArray", HowMany.Text);
            commandquery.Parameters.AddWithValue("NumberOfErrors", 0);
            commandquery.Parameters.AddWithValue("ClassID", classID);
            commandquery.Parameters.AddWithValue("SchoolID", schoolID);
            commandquery.Parameters.AddWithValue("Arrayarray", arr);

            commandquery.ExecuteNonQuery();





            int IdOfRecentHistoryGame = (Int32)commandquery.ExecuteScalar();
            con.Close();

            Response.Redirect("NowPlay.aspx?ID="+ IdOfRecentHistoryGame);

有人有线索？

谢谢！

推荐答案

SCOPE_IDENTITY（）收益数字（38,0）因为一个身份可以在类型列，除了 INT （见<一href=\"http://beyondrelational.com/blogs/jacob/archive/2009/01/28/sql-server-what-are-the-data-types-supported-in-identity-columns.aspx\"相对=nofollow> SQL服务器 - ？什么是IDENTITY列支持的数据类型）

SCOPE_IDENTITY() returns numeric(38,0) since an IDENTITY can be defined on columns of types besides int (see SQL Server - What are the data types supported in IDENTITY columns?).

的ExecuteScalar 返回一个小数为对象 ，你不能直接转换为 INT 。相反，强制转换为小数，然后才 INT ：

ExecuteScalar is returning a decimal as an object, which you cannot cast directly to int. Instead, cast to decimal first, then to int:

int IdOfRecentHistoryGame = (Int32)(Decimal)commandquery.ExecuteScalar();

这篇关于试图通过最近与ID SCOPE_IDENTITY，它的错误我：指定的转换是无效的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！