Question

帮助！它说连接没有关闭。连接的当前状态是ope，但我确实关闭了，请帮助？提前谢谢你

private void inserttransaction()
    {

        for (int i = 0; i < dataPOS.Rows.Count; i++)
        {
            con.Open();
            dataPOS.Rows[i].Selected = true;
            cmd = new SqlCommand(@"INSERT INTO TRANSACTIONS (TransactionCode,TransactionDate,ItemCode,ItemName,Quantity,Price,Total)
                                 VALUES
                                    ('"+ dataPOS.SelectedRows[0].Cells[0].Value.ToString() +"' , '"+ dataPOS.SelectedRows[0].Cells[1].Value.ToString() +"' , '"+ dataPOS.SelectedRows[0].Cells[2].Value.ToString() +"' , '"+ dataPOS.SelectedRows[0].Cells[3].Value.ToString()+"' , '"+ dataPOS.SelectedRows[0].Cells[4].Value.ToString() +"' '"+ dataPOS.SelectedRows[0].Cells[5].Value.ToString() +"' , '"+ dataPOS.SelectedRows[0].Cells[6].Value.ToString() +"')", con);
            cmd.ExecuteNonQuery();
            dataPOS.Rows[i].Selected = false;
            con.Close();
        }

    }

Answer 1

您无法打开已打开的连接。

con.Open();

for (int i = 0; i < dataPOS.Rows.Count; i++)
{
    dataPOS.Rows[i].Selected = true;
    cmd = new SqlCommand(@"INSERT INTO TRANSACTIONS (TransactionCode,TransactionDate,ItemCode,ItemName,Quantity,Price,Total)
                         VALUES
                            ('"+ dataPOS.SelectedRows[0].Cells[0].Value.ToString() +"' , '"+ dataPOS.SelectedRows[0].Cells[1].Value.ToString() +"' , '"+ dataPOS.SelectedRows[0].Cells[2].Value.ToString() +"' , '"+ dataPOS.SelectedRows[0].Cells[3].Value.ToString()+"' , '"+ dataPOS.SelectedRows[0].Cells[4].Value.ToString() +"' '"+ dataPOS.SelectedRows[0].Cells[5].Value.ToString() +"' , '"+ dataPOS.SelectedRows[0].Cells[6].Value.ToString() +"')", con);
    cmd.ExecuteNonQuery();
    dataPOS.Rows[i].Selected = false;
}

con.Close();

但我仍然使用using语句：

using(var con = new SqlConnection("connection-string.."))
{
    con.Open();

    for (int i = 0; i < dataPOS.Rows.Count; i++)
    {
        dataPOS.Rows[i].Selected = true;
        cmd = new SqlCommand(@"INSERT INTO TRANSACTIONS (TransactionCode,TransactionDate,ItemCode,ItemName,Quantity,Price,Total)
                             VALUES
                                ('"+ dataPOS.SelectedRows[0].Cells[0].Value.ToString() +"' , '"+ dataPOS.SelectedRows[0].Cells[1].Value.ToString() +"' , '"+ dataPOS.SelectedRows[0].Cells[2].Value.ToString() +"' , '"+ dataPOS.SelectedRows[0].Cells[3].Value.ToString()+"' , '"+ dataPOS.SelectedRows[0].Cells[4].Value.ToString() +"' '"+ dataPOS.SelectedRows[0].Cells[5].Value.ToString() +"' , '"+ dataPOS.SelectedRows[0].Cells[6].Value.ToString() +"')", con);
        cmd.ExecuteNonQuery();
        dataPOS.Rows[i].Selected = false;
    }
}  // con.Close() not necessary

您还应该使用参数化查询而不是连接字符串来构建您的SQL查询。否则你很容易受到sql注入攻击。

Answer 2

尝试在循环之前添加using子句并打开conn。我认为您应该考虑添加SqlParameter，直接从源集合中添加数据（sql注入风险）。

            using (var con = new SqlConnection("your conn string"))
            {
                con.Open();
                SqlCommand cmd = new SqlCommand();
                cmd.CommandType = CommandType.Text;
                cmd.Connection = con;

                List<SqlParameter> sqlParams = new List<SqlParameter>();
                sqlParams.Add(new SqlParameter("@param0", null));
                sqlParams.Add(new SqlParameter("@param1", null));
                sqlParams.Add(new SqlParameter("@param2", null));
                sqlParams.Add(new SqlParameter("@param3", null));
                sqlParams.Add(new SqlParameter("@param4", null));
                sqlParams.Add(new SqlParameter("@param5", null));
                sqlParams.Add(new SqlParameter("@param6", null));

                cmd.Parameters.AddRange(sqlParams.ToArray());

                for (int i = 0; i < dataPOS.Rows.Count; i++)
                {
                    cmd.Parameters["@param0"].Value = dataPOS.SelectedRows[0].Cells[0].Value.ToString();
                    cmd.Parameters["@param1"].Value = dataPOS.SelectedRows[0].Cells[1].Value.ToString();
                    cmd.Parameters["@param2"].Value = dataPOS.SelectedRows[0].Cells[2].Value.ToString();
                    cmd.Parameters["@param3"].Value = dataPOS.SelectedRows[0].Cells[3].Value.ToString();
                    cmd.Parameters["@param4"].Value = dataPOS.SelectedRows[0].Cells[4].Value.ToString();
                    cmd.Parameters["@param5"].Value = dataPOS.SelectedRows[0].Cells[5].Value.ToString();
                    cmd.Parameters["@param6"].Value = dataPOS.SelectedRows[0].Cells[6].Value.ToString();

                    dataPOS.Rows[i].Selected = true;
                    cmd.CommandText = @"INSERT INTO TRANSACTIONS (TransactionCode,TransactionDate,ItemCode,ItemName,Quantity,Price,Total)
                                        VALUES (@param0, @param1, @param2, @param3, @param4, @param5,@param6 )";
                    cmd.ExecuteNonQuery();
                    dataPOS.Rows[i].Selected = false;
                }
            }

连接没有关闭。连接的当前状态是打开的

2 个答案: