sql创建一个表并添加删除字段

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient;

namespace WindowsFormsApplication1
{
public partial class Form1 : Form
{
SqlConnection myconnection;
SqlCommand mycommand;
SqlDataReader myreader;
string str = Properties.Settings.Default.connection;
public Form1()
{
InitializeComponent();
}

private void button1_Click(object sender, EventArgs e)
{
myconnection = new SqlConnection(str);
myconnection.Open();
string biao = this.textBox1.Text.Trim();
//创建带有一个自增字段的表
mycommand = new SqlCommand("create table ["+biao+"]([123] int IDENTITY (1,1) PRIMARY KEY,[12] nvarchar(50))", myconnection);
// mycommand.Parameters.AddWithValue("@gongsi",this.textBox1.Text.Trim());
myreader = mycommand.ExecuteReader();
}

private void button2_Click(object sender, EventArgs e)
{
myconnection = new SqlConnection(str);
myconnection.Open();
string ziduan = this.textBox2.Text.Trim();
//往表里添加新字段
mycommand = new SqlCommand("alter table [阿里巴巴网络技术有限公司] add [" + ziduan + "] nvarchar(50)",myconnection);
myreader = mycommand.ExecuteReader();
}

private void button3_Click(object sender, EventArgs e)
{
myconnection = new SqlConnection(str);
myconnection.Open();
//判断一个字段是否在一个表里
mycommand = new SqlCommand("SELECT COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE (TABLE_NAME =@biao and COLUMN_NAME=@ziduan)",myconnection);
mycommand.Parameters.AddWithValue("@biao", this.textBox2.Text);
mycommand.Parameters.AddWithValue("@ziduan", this.textBox3.Text);
myreader = mycommand.ExecuteReader();
if (myreader.Read())
{
MessageBox.Show("1");
}
else
{
MessageBox.Show("2");
}
}
}
}