C#中的经典代码.doc

C#中的经典代码普通控件的增删改查：例如：文本框，下拉框等，所有的操作，首先导入命名空间：using System.Data.SqlClient;增加代码：/连接字符串 SqlConnection conn = new SqlConnection(Data Source=.;Initial Catalog=数据库名称;Integrated Security=True); try conn.Open(); string sql = string.Format(insert into 表名 values( 0,1,2), this.textBox1.Text, int.Parse(this.textBox2.Text), this.textBox3.Text); SqlCommand comm = new SqlCommand(sql, conn); int number = comm.ExecuteNonQuery(); if (number 0) MessageBox.Show(插入成功); else MessageBox.Show(插入失败); catch (Exception ex) MessageBox.Show(数据库异常); finally /连接始终要关闭 conn.Close(); 注意：在插入的SQL语句中，占位符需要注意：字符型的要加单引号，数字型的不加。在给占位符赋值时需要注意：数字型的要强转。删除代码：/连接字符串 SqlConnection conn = new SqlConnection(Data Source=.;Initial Catalog=数据库名称;Integrated Security=True); try conn.Open(); string sql = string.Format(delete from 表名 where 列名=0 , int.Parse(this.textBox2.Text); SqlCommand comm = new SqlCommand(sql, conn); int number = comm.ExecuteNonQuery(); if (number 0) MessageBox.Show(删除成功); else MessageBox.Show(删除失败); catch (Exception ex) MessageBox.Show(数据库异常); finally /连接始终要关闭 conn.Close(); 修改的代码： /连接字符串 SqlConnection conn = new SqlConnection(Data Source=.;Initial Catalog=数据库名;Integrated Security=True); try conn.Open(); string sql = string.Format(update 表名 set 数据库列名=0,数据库列名=1,this.textBox1.Text, int.Parse(this.textBox2.Text); SqlCommand comm = new SqlCommand(sql, conn); int number = comm.ExecuteNonQuery(); if (number 0) MessageBox.Show(更新成功); else MessageBox.Show(更新失败); catch (Exception ex) MessageBox.Show(数据库异常); finally /连接始终要关闭 conn.Close(); 查询出某列绑定到下拉列表控件中string name=; SqlConnection conn = new SqlConnection(Data Source=.;Initial Catalog=数据库名;Integrated Security=True); try conn.Open(); string sql=select 某列 from 表名; SqlCommand comm = new SqlCommand(sql, conn); SqlDataReader dr=comm.ExecuteReader(); while (dr.Read() name=dr数据库某列名.ToString(); /加载到页面的下拉列表控件中 boBox1.Items.Add(name); dr.Close(); catch (Exception ex) MessageBox.Show(数据库异常); finally conn.Close(); 如果绑定的是datagridview控件：查询代码：SqlConnection conn = new SqlConnection(Data Source=.;Initial Catalog=AddressBookDB;Integrated Security=True); string sql=select * from 表名; SqlDataAdapter da=new SqlDataAdapter(sql,conn); DataSet ds=new DataSet(); da.Fill(ds,表名); this.dataGridView1.DataSource=ds.Tables0;更新代码： SqlConnection conn=new SqlConnection (Data Source=.;Initial Catalog=AddressBookDB;Integrated Security=True); SqlDataAdapter da=new SqlDataAdapter(); SqlCommandBuilder comm=new SqlCommandBuilder(da); da.Update(ds,表名);清空代码：重置按钮也叫清空按钮： this.textBox1.Text = ; boBox1.Text = ;窗体的关闭：this.Close();应用程序的关闭： Application.Exit();MDI子窗体显示：IsMdiContainer:true Form2 objfom = new Form2();/实例化子窗体 objfom.MdiParent = this;/设置父窗体为this objfom.Show();/普通显示 objfom.ShowDialog();/模式窗体显示窗体最大化：WindowState:Maximized窗体首次加载：StartPosition:四个属性 /为空判断 private bool NewMethod() if (this.textBox1.Text.Trim() = ) MessageBox.Show(姓名不能为空); this.textBox1.Focus(); return false; else if (this.textBox2.Text.Trim() = ) if (this.textBox2.Text).Length != 15 | (this.textBox2.Text).Length != 18) MessageBox.Show(身份证号码必须为15位或18位); this.textBox2.Focus(); return false; else ret