c#的dataset离线数据集示例

c# dataset离线数据集实例

using system;
using system.collections.generic;
using system.linq;
using system.text;
using system.windows;
using system.windows.controls;
using system.windows.data;
using system.windows.documents;
using system.windows.input;
using system.windows.media;
using system.windows.media.imaging;
using system.windows.navigation;
using system.windows.shapes;
using system.data.sqlclient;
using system.data; using system.configuration;

namespace _03.dataset离线数据集
{
    /// <summary>
    /// window1.xaml 的交互逻辑
    /// </summary>
    public partial class window1 : window
    {
        public window1()
        {
            initializecomponent();
        }

        private void btnds_click(object sender, routedeventargs e)
        {
            using (sqlconnection conn = new sqlconnection("data source=.;initial catalog=mytest;user id=sa;password=123;"))
            {
                conn.open();
                using (sqlcommand cmd = conn.createcommand())
                {
                    cmd.commandtext = "select * from t_student where age<@age";
                    cmd.parameters.add(new sqlparameter("@age", 60));
                    //cmd.executereader();并没有执行，而是new了一个adapter来接受cmd。

                    //sqldataadapter是一个帮我们把sqlcommand的查询结果填充到dataset中的类
                    sqldataadapter adapter = new sqldataadapter(cmd);//sqldataadapter需要一个参数

                    //dataset相当于本地的一个复杂集合（list<int>）
                    dataset dataset = new dataset();//dataset是数据集
                    adapter.fill(dataset);//执行cmd并且把sqlcommand查询结果填充到dataset

                    //datatable是内存中的数据表
                    datatable table = dataset.tables[0];//因为数据库中就一个表t_student，所以就是[0].
                    datarowcollection rows = table.rows;//datarowcollection是datatable行的集合,这里的rows指查询结果的行
                    for (int i = 0; i < rows.count; i++)
                    {
                        datarow row = rows[i];
                        int age = (int)row["age"];
                        string name=(string)row["name"];
                        messagebox.show(name+","+age);
                    }
                }
            }
        }

        private void btndss_click(object sender, routedeventargs e)
        {
            //采用configurationmanager.connectionstrings 属性,只能读取到app.config的配置信息。
            string connstr = configurationmanager.connectionstrings["dbconnstr"].connectionstring;
            //项目根目录添加一个"应用程序配置文件",名字是app.config
            //app.config加节点，给add起一个name
            //项目添加对system.configuration的引用(理解为添加开发包,system.data就是ado.net的开发包)
            //就能使用system.configuration里的configurationmanager类
            //asp.net里就变成了web.config

            messagebox.show(connstr);
            using (sqlconnection conn = new sqlconnection(connstr))
            {
                conn.open();
                using (sqlcommand cmd = conn.createcommand())
                {
                    cmd.commandtext = "select * from t_student where age<@age";
                    cmd.parameters.add(new sqlparameter("@age",21));

                    sqldataadapter adapter = new sqldataadapter(cmd);
                    dataset dataset = new dataset();
                    adapter.fill(dataset);

                    datatable table=dataset.tables[0];
                    datarowcollection rows = table.rows;
                    for(int i=0;i<rows.count;i++)
                    {
                        datarow row=rows[i];
                        string hobbit=(string)row["hobbit"];
                        messagebox.show(hobbit);
                    }
                }
            }
        }
    }
}