如何遍历SQL表以设置全局变量 [英] How do I loop through SQL table to set global variables

问题描述

大家好



我有一张桌子tblFlags有3列UniqID，FlagName，FlagValue



此表用于存储应用程序设置，即DataPathBackup



我想要做的是循环此表以在启动时设置公共静态字符串



即公共静态字符串FlagName=FlagValue

这应该返回：public static string DataPathBackup = z：\ AppBackup \





我怎样才能实现这个目标？



我有什么尝试过：



我设置了一些默认值

ie

public static String DataPathBackup = @Z：\ AppBackup \;



然后我打电话给FillFlags（）



来自下面;

j返回正确的FlagName，k返回正确的FlagValue





所以我希望有类似

公共静态字符串j=k



这将覆盖我的默认设置，如果在此表中找到它

Hi All

I have a table tblFlags with 3 columns UniqID, FlagName,FlagValue

This table is used for storing app settings ie DataPathBackup

What i would like to do is loop through this table to set public static strings upon startup

ie public static string "FlagName" = "FlagValue"
this should return : public static string DataPathBackup = z:\AppBackup\


How would i be able to achieve this?

What I have tried:

I have set some default values
ie
public static String DataPathBackup= @"Z:\AppBackup\";

then i call FillFlags()

From below;
j returns the correct FlagName and k returns the correct FlagValue


so i would like to have something like
public static string "j" = "k"

this will then overide my default setting if it was found in this table

public void FillFlags()
{
    string connectionString = null;
    SqlConnection cnn,cnn2;
    connectionString = CString;
    cnn = new SqlConnection(connectionString);
    cnn2 = new SqlConnection(connectionString);
    SqlDataReader dr,dr2;

        SqlCommand comm = new SqlCommand("SELECT [FlagName],[FlagValue] from tblFlags");

    comm.Connection = cnn;
        cnn.Open();
        dr = comm.ExecuteReader();

        while (dr.Read())
        {
            string j = dr["FlagName"].ToString();
           
            SqlCommand comm1 = new SqlCommand("SELECT [FlagValue] from tblFlags WHERE FlagName='"+ j +"'");
            comm1.Connection = cnn2;
            cnn2.Open();
            dr2 = comm1.ExecuteReader();
            MessageBox.Show(j);
            while (dr2.Read())
            {
                
                string k=dr2["FlagValue"].ToString();
                //j = k;
               
                MessageBox.Show(k);
            }
            dr2.Close();
            dr2.Dispose();
            cnn2.Close();
        }
        dr.Close();
        dr.Dispose();

        cnn.Close();
}

推荐答案

尽管可能会这样做，但这并不是一个好主意。我怀疑使用反射可以做到你想做的事情：

Although it's probably possible to do this, that doesn't make it a good idea. I suspect it's possible to do exactly what you want using reflection:

public static string MyVariable;
...
MyVariable = "Old value";
SetVariableByName("MyVariable", "New value for MyVariable");
Console.WriteLine(MyVariable);

并获得

And get

"New value for MyVariable"

打印。 （但是你必须编写这个方法，它会很复杂）



但它不好，慢，容易出错。

相反，请考虑使用词典：

printed. (But you'd have to write the method, and it would be complicated)

But it's not nice, slow, and prone to errors.
Instead, consider using a Dictionary:

public static Dictionary<string, object> MySettings = new Dictionary<string, object>();

并使用您从中检索的名称和值您的数据库设置条目：

And use the name and value you retrieve from your DB to set entries in that:

MySettings["MyVariable"] = "New value for MyVariable";

理解正在发生的事情要容易得多，而且更安全！

It's a lot easier to understand what is going on, and a lot safer!

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