public SqlConnection connection_database(string server,string database,string userid,string password)
{
string str_con;
str_con="server="+server+";"+"database="+database+";"+"user id="+userid+";"+"

password="+password;
try
{
SqlConnection sqlcon=new SqlConnection (str_con);
sqlcon.Open();

return sqlcon;
}
catch
{
MessageBox.Show("数据库连接不成功!请正确填写好数据库设置","错误",MessageBoxButtons.

OK,MessageBoxIcon.Stop);
Application.Exit();//应用程序退出
return null;
}

}
public DataView DvList(string logString,string tablename) //返回相应表的视图.
{
if( sqlconn.State == ConnectionState.Closed)
sqlconn.Open();
SqlDataAdapter myCommand = new SqlDataAdapter(logString, sqlconn);
DataSet ds = new DataSet();
try
{
myCommand.Fill(ds, "+tablename+");
}
catch
{
MessageBox.Show("error");
}
DataView Dv = new DataView();
Dv = ds.Tables["+tablename+"].DefaultView;
return Dv;
}

public void Execute_SQL(string sql,SqlConnection sqlconn)//通用执行SQL函数
{
// 打开数据库连接
if( sqlconn.State == ConnectionState.Open)
sqlconn.Close();
sqlconn.Open();
SqlCommand cmd = new SqlCommand(sql, sqlconn);
try
{
cmd.ExecuteNonQuery();
}
catch(SqlException ae)
{
MessageBox.Show(ae.Message.ToString());
}
cmd.Dispose();
}
public void show_listview_data(string select_str,string tablename,ListView lv)//通用的返回

树视图函数
{
//lv=new ListView();
lv.Clear();
this.sqlDataAdapter1=new SqlDataAdapter(select_str,this.sqlconn);
sqlDataAdapter1.Fill(dataSet21,"+tablename+");
//添加列名
for(int i=0;i<dataSet21.Tables["+tablename+"].Columns.Count;i++)
{
lv.Columns.Add(dataSet21.Tables["+tablename+"].Columns[i].ColumnName.

ToString(),90,HorizontalAlignment.Left);

}
//添加行（数据库数据）
for(int j=0;j<dataSet21.Tables["+tablename+"].Rows.Count;j++)
{
ListViewItem item=lv.Items.Add(dataSet21.Tables["+tablename+"].Rows[j][0].

ToString());
item.Text=dataSet21.Tables["+tablename+"].Rows[j][0].ToString();
for(int i=1;i<dataSet21.Tables["+tablename+"].Columns.Count;i++)
item.SubItems.Add(dataSet21.Tables["+tablename+"].Rows[j][i].

ToString());
}
lv.View=View.Details;


}

}