.net是如何连接SQL数据库的？

Question

.net是如何连接SQL数据库的？

Answer 1

在web.config文件中的<appSettings>节点下，添加如下内容：
<add key="ConnKey" value="Data Source=KO\MSSQLSERVER005;Initial Catalog=Web; User Id=sa;Password=sa;" />
下面是数据库连接文件，先定义公共变量SqlConn和ConnKeyStr ，请注意引号内“ConnKey”与web.config设定值需一致。
public SqlConnection SqlConn;
public static string ConnKeyStr = ConfigurationManager.AppSettings["ConnKey"].ToString();

下面两个函数，一个是打开数据连接，另一个是关闭数据连接。
//打开连接
public void SqlConnOpen()
{
if (SqlConn == null)
{
SqlConn = new SqlConnection(ConnKeyStr);
if (SqlConn.State != ConnectionState.Open)
{
try
{
SqlConn.Open();
}
catch
{
throw new Exception("打开数据库失败！");
}
}
}
else if(SqlConn.State!=ConnectionState.Open)
{
try
{
SqlConn.Open();
}
catch
{
throw new Exception("打开数据库失败！");
}
}
}

//关闭连接
public void SqlConnClose()
{
if (SqlConn.State != ConnectionState.Closed)
{
SqlConn.Close();
}
}

Answer 2

using System.Data.SqlClient;

SqlConnection cn = new SqlConnection("data source=(local);initial catalog=database_breakfast;user=sa;pwd=");
SqlCommand cmd = new SqlCommand(" select * from t_product_sort ", cn);
SqlDataAdapter da = new SqlDataAdapter(cmd);
DataSet ds = new DataSet();
da.Fill(ds, "prosort");
this.GridView1.DataSource = ds.Tables[0].DefaultView;
this.DataBind();