填充数据表 [英] Populate DataTable

问题描述

大家好，我无法在数据库中填充DataTable.

Hi everyone, I''m having trouble populating a DataTable with a database.

public DataTable GetData()
    {
        string connectionString =
          System.Web.HttpContext.Current.Application["solarsearch_dbConnectionString"].ToString();

        SqlConnection commandString =
            new SqlConnection(connectionString);

        commandString.Open();

        string SQL = "select * from enquiry";

        SqlCommand objCommand = new SqlCommand(SQL, commandString);
        SqlDataAdapter adapter = new SqlDataAdapter();
        DataSet DS = new DataSet();
        adapter.SelectCommand = objCommand;
        adapter.Fill(DS);

        DataTable dt = DS.Tables[0];
        return dt;
    }

当我执行代码时，出现错误信息，

When I execute the code I get the error by

string connectionString =       System.Web.HttpContext.Current.Application["solarsearch_dbConnectionString"].ToString();

说对象引用未设置为对象的实例.
请提供任何帮助.

saying Object reference not set to an instance of an object.
Any help please.

推荐答案

该错误表示"System.Web.HttpContext.Current.Application ["solarsearch_dbConnectionString"]无效-它以无效的. a测，"solarsearch_dbConnectionString"不在您的配置中...

顺便说一句:我会使用System.Configuration.Appsettings ["tag"] ..
因为它适用于两个网站的类内
应用程序和Windows应用程序.在某个时候，
您可能需要在Web上使用业务逻辑
桌面上的应用程序.

The error means that "System.Web.HttpContext.Current.Application["solarsearch_dbConnectionString"]" is not valid - it is returning as a null. At a guess, "solarsearch_dbConnectionString" is not in your configuration...

BTW: I would use System.Configuration.Appsettings["tag"]..
because it is applicable inside a class for both web
applications and windows applications. At some point,
you may need to use your business logic for the web
app on the desktop.

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