DataSet和DataTable区别 da.Fill(ds, "alias_1"); //使用DataAdapter的Fill方法(填充)，调用SELECT命令，别名 dataGridView8.DataSource = ds.Tables[0]; da.Fill(dt); //直接填充给dt flex.DataSource = dt; ds.Tables[0]==dt
DateSet是数据在内存中的缓存，是保存数据的数据结构，相当于一个虚拟的数据库，他可以包含多个DateTable 好像winform里面绑定只能绑定dataTable 简单而言,dataset和datatable都是ADO的非连接层,dataset是一个位于内存中表示外部数据的对象，它是一个类型，该类型维护三个内部强类型集合，其中包括了datatablecollection, dataset的tables属性能够访问包含多个datatable的datatablecollection
private void button1_Click(object sender, EventArgs e)
{
SqlConnection conn = new SqlConnection("server=.;database=CB_WMDDGLXT;uid=sa;pwd=sunlike$3285");
conn.Open();
if (conn.State==ConnectionState.Open)
{
label1.Text = "数控库已经连接并打开";
}
}
private void button2_Click(object sender, EventArgs e)
{
SqlConnection conn = new SqlConnection("server=.;database=CB_WMDDGLXT;uid=sa;pwd=sunlike$3285");
conn.Open();
if (conn.State == ConnectionState.Open)
{
label2.Text = "数控库已经连接并打开";
}
conn.Close();
if (conn.State==ConnectionState.Closed)
{
label2.Text = "数控打开后又关闭了";
}
}
private void button3_Click(object sender, EventArgs e)
{
SqlConnection conn = new SqlConnection("server=.;database=CB_WMDDGLXT;uid=sa;pwd=sunlike$3285");
conn.Open();
if (conn.State == ConnectionState.Open)
{
label3.Text = "数控库已经连接并打开";
}
conn.Dispose();
label3.Text = "conn.Dispose()";
}
private void button4_Click(object sender, EventArgs e)
{
SqlConnection conn = new SqlConnection("server=.;database=CB_WMDDGLXT;uid=sa;pwd=sunlike$3285");
conn.Open();
if (conn.State == ConnectionState.Open)
{
label4.Text = "数控库已经连接并打开";
}
SqlCommand cmd = new SqlCommand();
cmd.Connection = conn;
cmd.CommandText = "select count(*) from khxjd";
cmd.CommandType = CommandType.Text;
int i = Convert.ToInt32(cmd.ExecuteScalar());
label4.Text = "表中有" + i.ToString() + "条记录！";
}
private void button5_Click(object sender, EventArgs e)
{
SqlConnection conn = new SqlConnection("server=.;database=CB_WMDDGLXT;uid=sa;pwd=sunlike$3285");
conn.Open();
if (conn.State == ConnectionState.Open)
{
label5.Text = "数控库已经连接并打开";
}
SqlCommand cmd = new SqlCommand();
cmd.Connection = conn;
cmd.CommandText = "update khxjd set qty=100+isnull(qty,0)";
cmd.CommandType = CommandType.Text;
int i = Convert.ToInt32(cmd.ExecuteNonQuery());
label5.Text = "更新了表中" + i.ToString() + "条记录！";
}
//sqlDataReader,是向前的。
//针对于一个sqlConnection,创建多个sqlDataReader,要先关闭上一个sqlDataReader，才能使用下一个sqlDataReader.
private void button6_Click(object sender, EventArgs e)
{
SqlConnection conn = new SqlConnection("server=.;database=CB_WMDDGLXT;uid=sa;pwd=sunlike$3285");
conn.Open();
if (conn.State == ConnectionState.Open)
{
label6.Text = "数控库已经连接并打开";
}
SqlCommand cmd = new SqlCommand();
cmd.Connection = conn;
cmd.CommandText = "select top 5 khxjdh,itm,nsn,prd_name_eng,prd_name_chs,qty from khxjd";
cmd.CommandType = CommandType.Text;
SqlDataReader sdr= cmd.ExecuteReader();
while (sdr.Read())
{
label6.Text = label6.Text + "," + sdr[1].ToString();
}
label6.Text = label6.Text + "。读取完成！";
}
private void button7_Click(object sender, EventArgs e)
{
SqlConnection conn = new SqlConnection("server=.;database=CB_WMDDGLXT;uid=sa;pwd=sunlike$3285");
conn.Open();
if (conn.State == ConnectionState.Open)
{
label7.Text = "数控库已经连接并打开";
}
SqlCommand cmd = new SqlCommand();
cmd.Connection = conn;
cmd.CommandText = "select top 5 khxjdh,itm,nsn,prd_name_eng,prd_name_chs,qty from khxjd";
cmd.CommandType = CommandType.Text;
SqlDataReader sdr = cmd.ExecuteReader();
if (sdr.HasRows)
{
label7.Text = "有数据";
}
else
{
label7.Text = "无数据";
}
sdr.Close();
}
//SqlDataAdapter:DataAdapter对象在DataSet与数据之间起桥梁作用
private void button8_Click(object sender, EventArgs e)
{
SqlConnection conn = new SqlConnection("server=.;database=CB_WMDDGLXT;uid=sa;pwd=sunlike$3285");
//conn.Open(); //说明一下：使用 SqlDataAdapter时，只要SqlConnection有效就行，不需要 打开！！！
if (conn.State == ConnectionState.Open)
{
label8.Text = "数控库已经连接并打开";
}
else
{
label8.Text = "数控库还未打开"; //ok
}
//SqlCommand cmd = new SqlCommand();
//cmd.Connection = conn;
//SqlCommand cmd = new SqlCommand( "select top 5 khxjdh,itm,nsn,prd_name_eng,prd_name_chs,qty from khxjd",conn);
//SqlDataAdapter da = new SqlDataAdapter();
//da.SelectCommand = cmd;
//DataSet ds = new DataSet();
// da.Fill(ds, "alias_1"); //使用DataAdapter的Fill方法(填充)，调用SELECT命令，别名
//dataGridView8.DataSource = ds.Tables[0];
SqlDataAdapter da = new SqlDataAdapter("select top 5 khxjdh,itm,nsn,prd_name_eng,prd_name_chs,qty from khxjd", conn); //创建DataAdapter数据适配器实例
if (conn.State == ConnectionState.Open)
{
label8.Text = label8.Text+ "2.数控库已经连接并打开";
}
else
{
label8.Text = label8.Text + "2.数控库还未打开"; //ok
}
DataSet ds = new DataSet(); //创建DataSet实例
da.Fill(ds, "alias_1"); //使用DataAdapter的Fill方法(填充)，调用SELECT命令，别名
dataGridView8.DataSource = ds.Tables[0];
//label8.Text = "数控查询完成";
if (conn.State == ConnectionState.Open)
{
label8.Text = label8.Text + "3.数控库已经连接并打开";
}
else
{
label8.Text = label8.Text + "3.数控库还未打开"; //ok
}
//conn.Close(); //关闭数据库
}
// load table from db
string sql = "select * from products";
string conn = GetConnectionString();
System.Data.OleDb.OleDbDataAdapter da = new System.Data.OleDb.OleDbDataAdapter(sql, conn);
DataTable dt = new DataTable();
da.Fill(dt); //直接填充给dt
// bind to grid
_flex.Cols[0].Width = 20;
_flex.ShowCursor = true;
_flex.DataSource = dt;
// add calculated field
dt.Columns.Add("ValueInStock", typeof(decimal), "UnitPrice * UnitsInStock");
_flex.Cols["ValueInStock"].Format = "c";
// add unbound column
Column col = _flex.Cols.Add();
col.Name = col.Caption = "Unbound";
时间： 2024-10-14 12:11:30