C# 从数据集中提取数据
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extracting data from data set
提问by Freelancer
Respected Users,
尊敬的用户，
I am extracting data using data set. I want to put value in textbox. But value is not comming.
我正在使用数据集提取数据。我想在文本框中输入值。但价值并没有到来。
I have following Code
我有以下代码
try
{
da = new SqlDataAdapter("select ID from Customer where Name='" + gvBkPendingSearch.SelectedRows[0].Cells[1].Value.ToString() + "'",con);
DataSet ds = new DataSet();
da.Fill(ds);
for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
txtCustomerID.Text = ds.Tables[0].Rows[0].ToString();
}
catch (Exception ex)
{
}
finally
{
}
txtCustomerID is my textbox. It is capturing value as>>>>>System.Data.DataRow
txtCustomerID 是我的文本框。它正在捕获价值为>>>>>System.Data.DataRow
Error is in txtCustomerID.Text = ds.Tables[0].Rows[0].ToString();
错误在 txtCustomerID.Text = ds.Tables[0].Rows[0].ToString();
but i am not able to understand it. Please help me.
但我无法理解。请帮我。
采纳答案by Pawan Nogariya
change it like this
像这样改变它
for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
txtCustomerID.Text = ds.Tables[0].Rows[i]["ID"].ToString();
The mistake you are doing is, you are accessing this
你正在做的错误是，你正在访问这个
ds.Tables[0].Rows[0].ToString();
means 0th row, the whole row!! not the column value
表示第 0 行，整行！！不是列值
And the datatable row is System.Data.DataRowin .Net
并且数据表行在System.Data.DataRow.Net 中
回答by Darin Dimitrov
You need to select the column:
您需要选择列：
txtCustomerID.Text = ds.Tables[0].Rows[i][0].ToString();
Also note that you are overwriting the value of the textbox on each iteration of the loop. So what you will end up with is the ID of the last record in this textbox.
另请注意，您将在循环的每次迭代中覆盖文本框的值。所以你最终会得到这个文本框中最后一条记录的 ID。
Also your query seems vulnerable to SQL injection. Personally I would recommend you scraping the DataSets in favor of an ORM or even plain old ADO.NET:
此外，您的查询似乎容易受到 SQL 注入的影响。我个人建议您刮取数据集以支持 ORM 甚至是普通的旧 ADO.NET：
public static IEnumerable<int> GetIds(string name)
{
using (var conn = new SqlConnection("Your connection string comes here"))
using (var cmd = conn.CreateCommand())
{
conn.Open();
cmd.CommandText = "select ID from Customer where Name=@Name";
cmd.Parameters.AddWithValue("@Name", name);
using (var reader = cmd.ExecuteReader())
{
while (reader.Read())
{
yield return reader.GetInt32(reader.GetOrdinal("ID"));
}
}
}
}
And now you could happily use this function:
现在你可以愉快地使用这个函数了：
string name = gvBkPendingSearch.SelectedRows[0].Cells[1].Value.ToString();
int id = GetIds(name).FirstOrDefault();
txtCustomerID.Text = id.ToString();
