英文:
i'm experiencing a weird behavior with winform c# timer
问题
I'm trying to update datagridview from sql server database using a timer. First, I got 2 strings
string pervCount = "0";string newCount = "0";
They are out of my timer; the rest is inside the timer (edit1). Then I'm counting the rows in my SQL table using:
conn.Open();SqlCommand cmd = new SqlCommand("SELECT COUNT(InvoiceID) FROM InvoicesHeaderTable;", conn);SqlDataReader dr = cmd.ExecuteReader();while (dr.Read()){newCount = dr.GetValue(0).ToString();}conn.Close();
Then I'm checking:
if (pervCount != newCount){conn.Open();SqlCommand cmd1 = new SqlCommand("select InvoiceID, CustomerName, TotalInvoicePrice from InvoicesHeaderTable where CompleteStatus=0", conn);SqlDataAdapter da = new SqlDataAdapter(cmd1);DataTable dt = new DataTable();da.Fill(dt);if (dt.Rows.Count > 0){CashierDgv.DataSource = dt;}conn.Close();pervCount = newCount;}
The if statement should not work since pervCount = newCount since I'm assigning both variables to be equal in the if statement. But somehow my datagridview is constantly refreshed.
英文:
i'm trying to update datagridview from sql server database using a timer. First i got 2 strings
string pervCount = "0";string newCount = "0";
they are out of my timer, the rest is inside the timer (edit1)
then i'm counting the rows in my sql table using:
conn.Open();SqlCommand cmd = new SqlCommand("SELECT COUNT(InvoiceID) FROM InvoicesHeaderTable;", conn);SqlDataReader dr = cmd.ExecuteReader();while (dr.Read()){newCount = dr.GetValue(0).ToString();}conn.Close();
then i'm checking:
if (pervCount != newCount){conn.Open();SqlCommand cmd1 = new SqlCommand("select InvoiceID, CustomerName,TotalInvoicePrice from InvoicesHeaderTable where CompleteStatus=0", conn);SqlDataAdapter da = new SqlDataAdapter(cmd1);DataTable dt = new DataTable();da.Fill(dt);if (dt.Rows.Count > 0){CashierDgv.DataSource = dt;}conn.Close();pervCount = newCount;}
the if statement should not work since pervCount = newCount since i'm a assigning both variables to be equal int the if statement. But some how my datagridview is constantly refreshed.
答案1
得分: 0
我使用了一个简化的代码，解决了我的问题，实现了我想要的效果。
int pervCount = 0;在我的定时器外部，然后在我的定时器内部：SqlCommand cmd = new SqlCommand("SELECT InvoiceID,CustomerName,TotalInvoicePrice FROM InvoicesHeaderTable where CompleteStatus =0", conn);SqlDataAdapter adab = new SqlDataAdapter(cmd);DataTable table = new DataTable();adab.Fill(table);if (table.Rows.Count > pervCount){CashierDgv.DataSource = table;pervCount = table.Rows.Count;}
英文:
i used a simpler code that fixed my problem and did exactly what i want.
int pervCount = 0;
out of my timer, then inside my timer:
SqlCommand cmd = new SqlCommand("SELECT InvoiceID,CustomerName,TotalInvoicePrice FROM InvoicesHeaderTable where CompleteStatus =0", conn);SqlDataAdapter adab = new SqlDataAdapter(cmd);DataTable table = new DataTable();adab.Fill(table);if (table.Rows.Count > pervCount){CashierDgv.DataSource = table;pervCount = table.Rows.Count;}
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