C# 从表单中提取填充方法
我在windows窗体上有一个组合框,我用名称列表填充它。目前,我在Form类中有以下代码,它运行良好C# 从表单中提取填充方法,c#,winforms,C#,Winforms,我在windows窗体上有一个组合框,我用名称列表填充它。目前,我在Form类中有以下代码,它运行良好 // This section opens a connection to the database, selects all the portfolio names that have an "in Use" value of 1, and then // fills Combo Box 2 with the values. SqlConnection my
// This section opens a connection to the database, selects all the portfolio names that have an "in Use" value of 1, and then
// fills Combo Box 2 with the values.
SqlConnection myConnection = new SqlConnection(@"Data Source = (LocalDB)\MSSQLLocalDB; AttachDbFilename = ""C:\Users\Nick\Documents\Investments 4.mdf""; Integrated Security = True; Connect Timeout = 30");
myConnection.Open();
SqlCommand myCommand2 = new SqlCommand();
myCommand2.Connection = myConnection;
myCommand2.CommandText = "SELECT Portfolio_Name FROM Dbo.Name WHERE In_use = 1";
SqlDataReader myReader2 = myCommand2.ExecuteReader();
while (myReader2.Read())
{
comboBox2.Items.Add(myReader2[0]);
}
myConnection.Close();
我希望能够将其提取到一个单独的方法中,并将其放入一个单独的类中,用于通用实用程序方法。然而,我被困在一个非常简单的问题上。当我将代码放入一个类中时,我需要能够告诉它我要填充哪个combox框,而我不知道如何传递这些信息。如果答案显而易见,我很抱歉,但我们将非常感激您的帮助
谢谢 如果你想提取,那么提取:
// Let's extract a class: it should provide us standard cursors,
// e.g. Protfolio Names
public static class MyData {
// Let's enumerate items returned
public static IEnumerable<string> PortfolioNames() {
// Wrap IDisposable into using
//TODO: move Connection String into a separated method/property
using (SqlConnection con = new SqlConnection(/*connection string here*/)) {
con.Open();
// Make sql readable
//DONE: when presenting something to user, sort it (order by) esp. strings
string sql =
@" select Portfolio_Name
from Dbo.Name
where In_use = 1
order by Portfolio_Name";
// Wrap IDisposable into using
using (SqlCommand q = new SqlCommand(sql, con)) {
// Wrap IDisposable into using
using (var reader = q.ExecuteReader()) {
while (reader.Read())
yield return Convert.ToString(reader[0]);
}
}
}
}
}
如果你想提取,那么提取:
// Let's extract a class: it should provide us standard cursors,
// e.g. Protfolio Names
public static class MyData {
// Let's enumerate items returned
public static IEnumerable<string> PortfolioNames() {
// Wrap IDisposable into using
//TODO: move Connection String into a separated method/property
using (SqlConnection con = new SqlConnection(/*connection string here*/)) {
con.Open();
// Make sql readable
//DONE: when presenting something to user, sort it (order by) esp. strings
string sql =
@" select Portfolio_Name
from Dbo.Name
where In_use = 1
order by Portfolio_Name";
// Wrap IDisposable into using
using (SqlCommand q = new SqlCommand(sql, con)) {
// Wrap IDisposable into using
using (var reader = q.ExecuteReader()) {
while (reader.Read())
yield return Convert.ToString(reader[0]);
}
}
}
}
}
您可以使用助手类名组合进行数据访问。GetNames方法不需要ComboBox实例。这增加了在另一个上下文中重用该方法的机会
public static class Portfolio
{
public static IList<string> GetNames()
{
SqlConnection myConnection = new SqlConnection(@"Data Source = (LocalDB)\MSSQLLocalDB; AttachDbFilename = ""C:\Users\Nick\Documents\Investments 4.mdf""; Integrated Security = True; Connect Timeout = 30");
myConnection.Open();
SqlCommand myCommand2 = new SqlCommand();
myCommand2.Connection = myConnection;
myCommand2.CommandText = "SELECT Portfolio_Name FROM Dbo.Name WHERE In_use = 1";
SqlDataReader myReader2 = myCommand2.ExecuteReader();
var portfolioNames = new List<string>();
while (myReader2.Read())
{
portfolioNames.Add(myReader2[0]);
}
myConnection.Close();
return portfolioNames;
}
}
您可以使用助手类名组合进行数据访问。GetNames方法不需要ComboBox实例。这增加了在另一个上下文中重用该方法的机会
public static class Portfolio
{
public static IList<string> GetNames()
{
SqlConnection myConnection = new SqlConnection(@"Data Source = (LocalDB)\MSSQLLocalDB; AttachDbFilename = ""C:\Users\Nick\Documents\Investments 4.mdf""; Integrated Security = True; Connect Timeout = 30");
myConnection.Open();
SqlCommand myCommand2 = new SqlCommand();
myCommand2.Connection = myConnection;
myCommand2.CommandText = "SELECT Portfolio_Name FROM Dbo.Name WHERE In_use = 1";
SqlDataReader myReader2 = myCommand2.ExecuteReader();
var portfolioNames = new List<string>();
while (myReader2.Read())
{
portfolioNames.Add(myReader2[0]);
}
myConnection.Close();
return portfolioNames;
}
}
事情很简单:
public class MyUtility
{
public static void FillComboBox(System.Windows.Forms.ComboBox comboBox)
{
//comboBox.Items.Clear(); //enable this line if required
using (SqlConnection myConnection = new SqlConnection(@"Data Source = (LocalDB)\MSSQLLocalDB; AttachDbFilename = ""C:\Users\Nick\Documents\Investments 4.mdf""; Integrated Security = True; Connect Timeout = 30"))
{
myConnection.Open();
using (SqlCommand myCommand2 = new SqlCommand())
{
myCommand2.Connection = myConnection;
myCommand2.CommandText = "SELECT Portfolio_Name FROM Dbo.Name WHERE In_use = 1";
using (SqlDataReader myReader2 = myCommand2.ExecuteReader())
{
while (myReader2.Read())
{
comboBox.Items.Add(myReader2[0]);
}
}
}
//myConnection.Close(); //not required inside using block
}
}
}
您可以使用其他方法获取连接字符串,例如从配置文件获取
用法非常简单,不需要额外的代码:
MyUtility.FillComboBox(comboBox2);
事情很简单:
public class MyUtility
{
public static void FillComboBox(System.Windows.Forms.ComboBox comboBox)
{
//comboBox.Items.Clear(); //enable this line if required
using (SqlConnection myConnection = new SqlConnection(@"Data Source = (LocalDB)\MSSQLLocalDB; AttachDbFilename = ""C:\Users\Nick\Documents\Investments 4.mdf""; Integrated Security = True; Connect Timeout = 30"))
{
myConnection.Open();
using (SqlCommand myCommand2 = new SqlCommand())
{
myCommand2.Connection = myConnection;
myCommand2.CommandText = "SELECT Portfolio_Name FROM Dbo.Name WHERE In_use = 1";
using (SqlDataReader myReader2 = myCommand2.ExecuteReader())
{
while (myReader2.Read())
{
comboBox.Items.Add(myReader2[0]);
}
}
}
//myConnection.Close(); //not required inside using block
}
}
}
您可以使用其他方法获取连接字符串,例如从配置文件获取
用法非常简单,不需要额外的代码:
MyUtility.FillComboBox(comboBox2);
当您不知道应该使用什么组合框时,请在函数中使用组合框值作为参数。当您不知道应该使用什么组合框时,请在函数中使用组合框值作为参数。啊,是的,这是我的下一阶段!谢谢,是的,这是我的下一个阶段!谢谢你的连接。关闭;是冗余的-将使用SqlConnection myConnection=。。。{...} scope@DmitryBychenko是的,我只是从原始代码中留下了它,它是从问题中复制粘贴的。谢谢你的连接。关闭;是冗余的-将使用SqlConnection myConnection=。。。{...} scope@DmitryBychenko是的,我只是从原始代码中留下了它,它是从问题中复制粘贴的。谢谢