Question

我已将此代码段编码为克隆表格中的选定行：

protected void Button4_Click(object sender, EventArgs e)
{
    DateTime ucode = DateTime.Now;
    string slctedProj = DropDownList1.SelectedItem.ToString();
    string new_code = "PR" + ucode.ToString("ssmmHHddMM");

    string query = @"INSERT INTO Projects (proj_id, proj_prod_id, proj_cust_id, proj_man_id,
                    proj_name, proj_date, proj_num_of_vehicles, proj_coach_vehicle,
                    proj_contract_value, proj_length, proj_width, proj_height, proj_passenger_seats,
                    proj_passenger_total, proj_type, proj_notes, uname, proj_brand, proj_systemvoltage,
                    proj_gauge, proj_service_speed)
                    SELECT proj_id, proj_prod_id, proj_cust_id, proj_man_id,
                    proj_name, proj_date, proj_num_of_vehicles, proj_coach_vehicle,
                    proj_contract_value, proj_length, proj_width, proj_height, proj_passenger_seats,
                    proj_passenger_total, proj_type, proj_notes, uname, proj_brand, proj_systemvoltage,
                    proj_gauge, proj_service_speed
                    FROM Projects WHERE proj_name =" + "'" + slctedProj + "'";
    System.Windows.Forms.MessageBox.Show(query);
    string getconnstring = ConfigurationManager.ConnectionStrings["stad_conn"].ConnectionString;
    SqlConnection conn = new SqlConnection(getconnstring);
    conn.Open();
    SqlCommand cmd = new SqlCommand(query, conn);
    cmd.ExecuteNonQuery();
    conn.Close();
}

代码工作正常，但我需要在新行中替换“proj_id”和字符串“new_code”，并在“proj_name”的开头附加“Cloned”。我怎么能这样做？

Answer 1

首先：Use parameters in your SQL command。

继承修改后的代码，带参数。请注意，参数上的Add方法既指定数据类型，也指定长度。 It's better to specify these explicitly而不是让ADO.Net认为它知道你想要什么。

DateTime ucode = DateTime.Now;
string slctedProj = DropDownList1.SelectedItem.ToString();
string new_code = "PR" + ucode.ToString("ssmmHHddMM");
string new_projectName = "Some new name";

string query = @"INSERT INTO Projects (proj_id, proj_prod_id, proj_cust_id, proj_man_id,
                proj_name, proj_date, proj_num_of_vehicles, proj_coach_vehicle,
                proj_contract_value, proj_length, proj_width, proj_height, proj_passenger_seats,
                proj_passenger_total, proj_type, proj_notes, uname, proj_brand, proj_systemvoltage,
                proj_gauge, proj_service_speed)
                SELECT @NewProjectID, proj_prod_id, proj_cust_id, proj_man_id,
                @NewProjectName, proj_date, proj_num_of_vehicles, proj_coach_vehicle,
                proj_contract_value, proj_length, proj_width, proj_height, proj_passenger_seats,
                proj_passenger_total, proj_type, proj_notes, uname, proj_brand, proj_systemvoltage,
                proj_gauge, proj_service_speed
                FROM Projects WHERE proj_name = @SelectedProj";

System.Windows.Forms.MessageBox.Show(query);

string getconnstring = ConfigurationManager.ConnectionStrings["stad_conn"].ConnectionString;
SqlConnection conn = new SqlConnection(getconnstring);
conn.Open();
SqlCommand cmd = new SqlCommand(query, conn);
cmd.Parameters.Add("@NewProjectID", SqlDbType.VarChar, 20).Value = new_code;
cmd.Parameters.Add("@NewProjectName", SqlDbType.VarChar, 20).Value = new_projectName;
cmd.Parameters.Add("@SelectedProj", SqlDbType.VarChar, 20).Value = slctedProj;

cmd.ExecuteNonQuery();
conn.Close();

Answer 2

这不是答案。您可以通过使用FK（仅适用于克隆项目）保留对源/初始项目的引用来改进此设计：

ALTER TABLE dbo.Projects
ADD source_proj_id INT NULL
REFERENCES dbo.Projects(proj_id);
GO

并且您还需要更改insert语句：

string query = @"INSERT INTO Projects 
                (proj_id, source_proj_id, proj_prod_id, ...)
                SELECT @NewProjectID, proj_id, proj_prod_id, ...
                FROM Projects WHERE proj_name = @SelectedProj";

SQL在克隆行时替换两条记录

2 个答案: