Question

我真的很困惑。我有3个名为id，title，images的表。我想做的是将图像存储在db中。但是我不能。我在这一行得到例外

int id = Convert.ToInt32(cmd.ExecuteScalar());

连接状态似乎是开放的。我还需要检查什么？

 SqlConnection connection = null;
        try
        {
            Byte[] imgByte = null;
            if (FileUpload1.HasFile && FileUpload1.PostedFile != null)
            {
                HttpPostedFile File = FileUpload1.PostedFile;
                imgByte = new Byte[File.ContentLength];
                File.InputStream.Read(imgByte, 0, File.ContentLength);
            }
            connection = new SqlConnection("server=.\\sqlexpress;database=Northwind;UID=sa;Password=1234");

            connection.Open();
            string sql = "INSERT INTO imgtable (title,images) VALUES(@theTitle, @theImage) SELECT @@IDENTITY";
            SqlCommand cmd = new SqlCommand(sql, connection);
            cmd.Parameters.AddWithValue("@theTitle", txtTitle.Text);
            cmd.Parameters.AddWithValue("@theImage", imgByte);
            int id = Convert.ToInt32(cmd.ExecuteScalar());

Answer 1

我的水晶球告诉我你得到一个关于无效SQL语法的错误。那是因为你不能通过在一行上写它们来执行两个语句。

在INSERT和SELECT之间添加分号：

string sql = "INSERT INTO imgtable (title,images) VALUES(@theTitle, @theImage); SELECT @@IDENTITY";

Answer 2

如果查看MSDN文档SQLCommand ExecuteScalar，他们会给出一个完整的示例：

static public int AddProductCategory(string newName, string connString)
{
    Int32 newProdID = 0;
    string sql =
        "INSERT INTO Production.ProductCategory (Name) VALUES (@Name); "
        + "SELECT CAST(scope_identity() AS int)";
    using (SqlConnection conn = new SqlConnection(connString))
    {
        SqlCommand cmd = new SqlCommand(sql, conn);
        cmd.Parameters.Add("@Name", SqlDbType.VarChar);
        cmd.Parameters["@name"].Value = newName;
        try
        {
            conn.Open();
            newProdID = (Int32)cmd.ExecuteScalar();
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message);
        }
    }
    return (int)newProdID;
}

Juste将int id = Convert.ToInt32(cmd.ExecuteScalar());替换为int id = (Int32)cmd.ExecuteScalar();。

同样编辑你的SQL语句：＆＃34; INSERT INTO imgtable（title，images）VALUES（@theTitle，@ theImage）; SELECT CAST（scope_identity（）AS int）＆＃34 ;;

处理图像时出了问题

2 个答案: