[英]Fetching data from SQL Server 2005 using c#
當其他兩個列的值相等時,我想從表中檢索特定列。 我的代碼如下。 四個列分別是id,destination,source,price
。
我想在目的地和來源相等時顯示價格。
請你幫助我好嗎?
private void button1_Click(object sender, EventArgs e)
{
SqlConnection con = new SqlConnection("Data source=.;initial catalog=loki;integrated security=true");
con.Open();
SqlDataAdapter da = new SqlDataAdapter();
DataTable dt = new DataTable();
da.SelectCommand = new SqlCommand("select price from metro where source='" + textBox1.Text + "' and destination='" + textBox2.Text + "'", con);
da.Fill(dt);
for(int i=0;i<dt.Rows.Count;i++)
{
textBox3.Text = dt.Rows[0][3].Count.ToString();
}
}
我想你在這之后....
private void button1_Click(object sender, EventArgs e)
{
using (SqlConnection con = new SqlConnection("Data source=.;initial catalog=loki;integrated security=true"))
{
string query = "select price from metro where source= @Source and destination = @Destination";
using (SqlCommand cmd = new SqlCommand(query, con))
{
cmd.Parameters.AddWithValue("@Source", textBox1.Text);
cmd.Parameters.AddWithValue("@Destination", textBox2.Text);
con.Open();
object o = cmd.ExecuteScalar();
if(o != null && o != DBNull.Value)
{
string price = (string) o; //please cast the return type as required
textBox3.Text = price;
}
con.Close();
}
}
}
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