C# 数据库连接笔记

// 连接
private OleDbConnection oleConnection1 = null;

public static string connection
{
get
{return"Data Source=dormMIS.mdb;Jet OLEDB:Engine Type=5;Provider=Microsoft.Jet.OLEDB.4.0;";}
}

DataSet ds //数据源

this.oleConnection1=new OleDbConnection(DormMIS.database.dbConnection.connection); // 指定数据库连接信息

oleConnection1.Open(); //打开连接

OleDbCommand cmd=new OleDbCommand("",oleConnection1);//定义查询数据类

string sql="select * from userinfo where UName='"+name.Text.Trim()+"' and PWD='"+password.Text.Trim()+"'"; //查询语句
cmd.CommandText=sql;

if (null!=cmd.ExecuteScalar())  //判断查询结果是否为空
{
//.........................遍历查询结果
OleDbDataReader dr;  //查询结果类
cmd.CommandText = sql; // 结果查询语句
dr = cmd.ExecuteReader(); //返回值附给dr
while (dr.Read()) //遍历返回的结果
{
Console.WriteLine(reader[0].ToString());
}
dr.Close();

//.........................放入数据表

ds= new DataSet(); //定义数据源
string sql="select dormID as 宿舍号,PCome as 来访人,PLook as 被访人,DateCome as 来访日期,DateLeave as 离开日期,"+                "Remark as 备注,RegisterID as 来访编号 from register";
OleDbDataAdapter adp=new OleDbDataAdapter(sql,oleConnection1);  //表示一组数据命令和数据连接用来填充DataSet
ds.Clear(); //清空数据源中的记录
adp.Fill(ds,"register");
//指定数据表的数据集
dataGrid1.DataSource = ds.Tables["register"].DefaultView;
dataGrid1.CaptionText = "共有"+ds.Tables["register"].Rows.Count+"条记录";
}
oleConnection1.Close(); //关闭链接

//..........................删除数据表中的记录  注：修改数据库同样用这样的语句
if (dataGrid1.DataSource!=null&&dataGrid1.CurrentRowIndex>=0&&dataGrid1[dataGrid1.CurrentCell]!=null)
{
oleConnection1.Open();
string sql = "delete * from register where RegisterID="+ds.Tables[0].Rows[dataGrid1.CurrentCell.RowNumber][6]+"";
OleDbCommand cmd = new OleDbCommand(sql,oleConnection1);
cmd.ExecuteNonQuery(); //执行和返回影响的行数
MessageBox.Show("删除成功","提示");
oleConnection1.Close();
}