ASP.NET与数据库相关技巧

一、取得数据表 i 行 j 列的值

//建立并打开数据库连接 
OleDbConnection conn=new OleDbConnection(); 
conn.ConnectionString=strConnectionString;//strConnectionString为数据库连接字符串 
conn.Open(); 

string sql="select * from NewsClass order by ClassId desc"; 
string x; 
DataSet ds=new DataSet(); 
OleDbDataAdapter da=new OleDbDataAdapter(sql,conn); 
da.Fill(ds,"NewsTable"); 
DataTable dt=ds.Tables["NewsTable"]; 
x=dt.Rows[i][1].ToString()//数据表i行j列的值 
conn.close(); 

 

//建立并打开数据库连接 OleDbConnection conn=new OleDbConnection(); conn.ConnectionString=strConnectionString;//strConnectionString为数据库连接字符串 conn.Open(); string sql="select * from NewsClass order by ClassId desc"; string x; DataSet ds=new DataSet(); OleDbDataAdapter da=new OleDbDataAdapter(sql,conn); da.Fill(ds,"NewsTable"); DataTable dt=ds.Tables["NewsTable"]; x=dt.Rows[i][1].ToString()//数据表i行j列的值 conn.close();

二、将数据读入DropDownList 

（1）DropDownList中添加数据

        

//建立并打开数据库连接 
OleDbConnection conn=new OleDbConnection(); 
conn.ConnectionString=strConnectionString;//strConnectionString为数据库连接字符串 
conn.Open(); 

string sql="select * from NewsClass order by ClassId desc"; 
//建立数据集 
DataSet ds=new DataSet(); 
OleDbDataAdapter da=new OleDbDataAdapter(sql,conn); 
da.Fill(ds,"NewsTable"); 
this.DropDownList1.DataSource=ds; 
this.DropDownList1.DataTextField = "ClassName";//Text值 
this.DropDownList1.DataValueField = "ClassID";//Value值 
this.DropDownList1.DataBind(); 

conn.Close(); 

//建立并打开数据库连接 OleDbConnection conn=new OleDbConnection(); conn.ConnectionString=strConnectionString;//strConnectionString为数据库连接字符串 conn.Open(); string sql="select * from NewsClass order by ClassId desc"; //建立数据集 DataSet ds=new DataSet(); OleDbDataAdapter da=new OleDbDataAdapter(sql,conn); da.Fill(ds,"NewsTable"); this.DropDownList1.DataSource=ds; this.DropDownList1.DataTextField = "ClassName";//Text值 this.DropDownList1.DataValueField = "ClassID";//Value值 this.DropDownList1.DataBind(); conn.Close();

（2）选中DropDownList的某项

       

this.DropDownList1.Items.FindByValue(dr["ClassID"].ToString().Trim()).Selected=true;

//dr为DataRow

this.DropDownList1.Items.FindByValue(dr["ClassID"].ToString().Trim()).Selected=true; //dr为DataRow this.DropDownList1.Items.FindByValue(dr["ClassID"].ToString().Trim()).Selected=true; //dr为DataRow this.DropDownList1.Items.FindByValue(dr["ClassID"].ToString().Trim()).Selected=true; //dr为DataRow

三、分类编码检索出相应的分类名称并在DataGrid中显示 

（1）.ASPX中的代码（ClassID为分类编码）

<asp:TemplateColumn HeaderText="类 别"> 
<ItemTemplate> 
<asp:Label id=lblClass runat="server" 
Text='<%# GetClassName(Convert.ToInt32(DataBinder.Eval(Container, 
"DataItem.ClassID"))) %>'> 
</asp:Label> 
</ItemTemplate> 
</asp:TemplateColumn> 

<asp:TemplateColumn HeaderText="类 别"> <ItemTemplate> <asp:Label id=lblClass runat="server" Text='<%# GetClassName(Convert.ToInt32(DataBinder.Eval(Container, "DataItem.ClassID"))) %>'> </asp:Label> </ItemTemplate> </asp:TemplateColumn>

（2）C#代码

///

/// "分类"列根据数字返回文字
///

///
///
public string GetClassName(int ClassID)
{
OleDbConnection conn=new OleDbConnection();
conn.ConnectionString=strConnectionString;
conn.Open();

string sql="select * from NewsClass where ClassID="+ClassID;
DataSet ds=new DataSet();
OleDbDataAdapter da=new OleDbDataAdapter(sql,conn);
da.Fill(ds,"ClassTable");
DataTable dt=ds.Tables["ClassTable"];
string strClassName=dt.Rows[0]["ClassName"].ToString();
conn.Close();

return strClassName;//返回 ClassID对应的ClassName
}

/// /// "分类"列根据数字返回文字 /// /// /// public string GetClassName(int ClassID) { OleDbConnection conn=new OleDbConnection(); conn.ConnectionString=strConnectionString; conn.Open(); string sql="select * from NewsClass where ClassID="+ClassID; DataSet ds=new DataSet(); OleDbDataAdapter da=new OleDbDataAdapter(sql,conn); da.Fill(ds,"ClassTable"); DataTable dt=ds.Tables["ClassTable"]; string strClassName=dt.Rows[0]["ClassName"].ToString(); conn.Close(); return strClassName;//返回 ClassID对应的ClassName }