摘要：
打印：打印对话框：打印对话框页面设置：页面设置对话框两个对话框都需要通过设置打印文档来指定打印对象打印文档：打印对象必须具有绘图板，以便在打印机和打印内容之间进行传输。打印机打印printdomentprintDocument1_PrintPage:事件，在打印每页之前触发，用于指定打印文档的打印内容
打印：
打印对话框：printdialog
页面设置：pagesetupdialog
这两个对话框都需要通过设置printdocument来指定打印对象
printdocument：打印对象，必须要有，一块画板，用于打印机与打印内容之间中转，打印机打印的是printdoment
printDocument1_PrintPage:事件，每打印一页之前触发，用于给printdocument指定打印内容
通过画板把内容画到打印对象的页上：
System.Drawing.Font f = new System.Drawing.Font("宋体",12);
e.Graphics.DrawString(textBox1.Text,f,System.Drawing.Brushes.Aqua,5,5);
最后打印： 打印对话框那，如果打印对话框返回确定打印，就执行printdocument.print();
看一下打印界面
下面是打印界面的代码 （点击小加号打开）
using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Data.SqlClient; using System.Drawing; using System.Linq; using System.Text; using System.Threading.Tasks; using System.Windows.Forms; namespace WindowsFormsApplication1 { public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void button1_Click(object sender, EventArgs e) { string username = textBox1.Text; string upass = textBox2.Text; //连接数据库 SqlConnection conn = new SqlConnection("server=.;database=data1220;user=sa;pwd=123"); conn.Open(); //执行语句 SqlCommand cmd = conn.CreateCommand(); cmd.CommandText = "select * from users where uname='" + username + "'and upass='" + upass + "'"; SqlDataReader dr = cmd.ExecuteReader(); if (dr.Read()) { //MessageBox.Show(dr["uname"].ToString()); MessageBox.Show("登陆成功"); } else { MessageBox.Show("登录失败"); } conn.Close(); } private void button2_Click(object sender, EventArgs e) { //添加数据到数据库 string username = textBox1.Text; string upass = textBox2.Text; //连接数据库 SqlConnection conn = new SqlConnection("server=.;database=data1220;user=sa;pwd=123"); conn.Open(); SqlCommand cmd = conn.CreateCommand(); cmd.CommandText = "insert into users values ('" + username + "'," + upass + ") "; int count = cmd.ExecuteNonQuery();//增删改 if (count > 0) { MessageBox.Show("添加成功"); } else { MessageBox.Show("添加失败"); } conn.Close(); } private void button3_Click(object sender, EventArgs e) { string code = textBox3.Text; string uname = textBox1.Text; string upass = textBox2.Text; //连接数据库 SqlConnection conn = new SqlConnection("server=.;database=data1220;user=sa;pwd=123"); conn.Open(); SqlCommand cmd = conn.CreateCommand(); cmd.CommandText = "update users set uname='" + uname + "',upass='" + upass + "'where code=" + code; int count = cmd.ExecuteNonQuery(); if (count > 0) { MessageBox.Show("修改成功"); } else { MessageBox.Show("修改失败"); } conn.Close(); } private void button4_Click(object sender, EventArgs e) { string code = textBox3.Text; //连接数据库 SqlConnection conn = new SqlConnection("server=.;database=data1220;user=sa;pwd=123"); conn.Open(); SqlCommand cmd = conn.CreateCommand(); cmd.CommandText = "delete from user where code=" + code; cmd.ExecuteNonQuery(); conn.Close(); } } }