3

I'd like to ask you how to convert a string into a decimal before update a table or insert data into table, after a user inserts a row, or update a row from a dataGridView.

For example, I put a decimal value 2.2 to the price column, then I save it to the database, then I refreshed the table, the value is 2, not the 2.2, or add 2.8, then the table shows us 3, not 2.8.

In my case, I want the column of price to be decimal, I do it as following, but it is not work, please help, thanks.

In form1.css:

..............
         //after a user click the save button
         private void btnSave_Click(object sender, EventArgs e) 
         { 
             Infor.UpdateDataSet((DataSet)dataGridView1.DataSource); 
          }
.........

Infor.css

  pInsert[3] = new SqlParameter("@p4", SqlDbType.Decimal, 40,
                                "price");
  pUpdate[2] = new SqlParameter("@p4", SqlDbType.Decimal, 40,
                                "price");

.........

   public static void UpdateDataSet(DataSet ds)
   {
      SqlConnection cnn = new SqlConnection(strConn);

      string sqlInsert, sqlUpdate, sqlDelete;
      sqlInsert = "insert into customers(customerid,companyname,
         contactname,price) values(@p1,@p2,@p3,@p4)";
      sqlUpdate = "update customers set companyname=@p2,
         contactname=@p3,price=@p4 where customerid=@p1";
      sqlDelete = "delete from customers where customerid=@p1";

      SqlParameter[] pInsert = new SqlParameter[4];
      SqlParameter[] pUpdate = new SqlParameter[4];
      SqlParameter[] pDelete = new SqlParameter[1];

      pInsert[0] = new SqlParameter("@p1", SqlDbType.VarChar,  5,
                                    "CustomerID");
      pInsert[1] = new SqlParameter("@p2", SqlDbType.VarChar, 40,
                                    "CompanyName");
      pInsert[2] = new SqlParameter("@p3", SqlDbType.VarChar, 40,
                                    "ContactName");
      pInsert[3] = new SqlParameter("@p4", SqlDbType.Decimal, 40,
                                    "price");

      pUpdate[0] = new SqlParameter("@p2", SqlDbType.VarChar, 40,
                                    "CompanyName");
      pUpdate[1] = new SqlParameter("@p3", SqlDbType.VarChar, 40,
                                    "ContactName");
      pUpdate[2] = new SqlParameter("@p4", SqlDbType.Decimal, 40,
                                    "price");
      pUpdate[3] = new SqlParameter("@p1", SqlDbType.VarChar,  5,
                                    "CustomerID");

      pDelete[0] = new SqlParameter("@p1", SqlDbType.VarChar,  5,
                                    "CustomerID");

      SqlCommand cmdInsert = new SqlCommand(sqlInsert,cnn);
      SqlCommand cmdUpdate = new SqlCommand(sqlUpdate,cnn);
      SqlCommand cmdDelete = new SqlCommand(sqlDelete,cnn);

      cmdInsert.Parameters.AddRange(pInsert);
      cmdUpdate.Parameters.AddRange(pUpdate);
      cmdDelete.Parameters.AddRange(pDelete);

      SqlDataAdapter da = new SqlDataAdapter();
      da.InsertCommand  = cmdInsert;
      da.UpdateCommand  = cmdUpdate;
      da.DeleteCommand  = cmdDelete;
      da.Update(ds, "customers");
      ds.AcceptChanges();
   }
4

1 回答 1

4

小数有两个因素，比例和精度。

精度是数字可以包含的位数。

比例是小数位数。

例子

  • 1111. 111 （精度：7，刻度3）
  • 11. 11111 （精度：7，刻度5）

您在创建参数时没有表示比例，只有一个精度（编辑：您实际上是在构造函数中以字节为单位指定大小，而不是精度）。您需要明确设置 Precision 和 Scale 属性以获得您想要的结果。

例子

取自http://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqlparameter.scale.aspx。

SqlParameter parameter = new SqlParameter("Price", SqlDbType.Decimal);
parameter.Value = 3.1416;
parameter.Precision = 8;
parameter.Scale = 4;

来自上述来源的相关说明：

如果未明确指定 Scale 属性并且服务器上的数据不适合比例 0（默认值），则数据可能会被截断。

这同样适用于表中的列定义，还必须指定精度和小数位数，当然，还要匹配。 （添加了@OlivierJacot-Descombes 的以下评论）

于 2012-12-30T15:55:18.267 回答