封装sqlhelper

控件信息展示：

//定义调用数据库类文件

namespace SqlHelper
{
public class TblClass
{
public int classId { get; set; }
public string class1 { get; set; }
public string classname { get; set; }
}
}

//主文件

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 SqlHelper
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
//定义一个连接字符串
//readonly修饰的变量，只能在初始化的时候赋值，以及在构造函数中赋值
//其他地方只能读取不能设置值
private static readonly string constr =@"database=ItcastCater;server=LAPTOP-2FGC7ARC\Wangjin;user=sa;pwd=sa";
//1. 执行增(insert)、删(delect)、改(update)的方法
//ExecteNonQuery()
public static int ExecteNonQuery(string sql, params SqlParameter[] pms)
{
using (SqlConnection conn = new SqlConnection(constr))
{
using (SqlCommand comm = new SqlCommand(sql, conn))
{
if (pms != null)
{
comm.Parameters.AddRange(pms);
}
conn.Open();
return comm.ExecuteNonQuery();
}
}
}
//返回单个值的方法封装 ExecuteScalar
public static object ExecuteScalar(string sql, params SqlParameter[] pms)
{
using (SqlConnection conn = new SqlConnection(constr))
{
using (SqlCommand comm = new SqlCommand(sql, conn))
{
if (pms != null)
{
comm.Parameters.AddRange(pms);
}
conn.Open();
return comm.ExecuteScalar();
}
}
}
//返回SqlDataReader类型的多行多列数据 因为reader使用的时候必须保持连接池打开，所以方法和以上不一样
public static SqlDataReader ExecuteReader(string sql, params SqlParameter[] pms)
{
SqlConnection conn = new SqlConnection(constr);

using (SqlCommand comm = new SqlCommand(sql, conn))
{
if (pms != null)
{
comm.Parameters.AddRange(pms);
}
try
{
conn.Open();
//System.Data.CommandBehavior.CloseConnection表示使用完毕以后在关闭reader的同时
//内部会将关联的connection对象页关闭掉
return comm.ExecuteReader(System.Data.CommandBehavior.CloseConnection);
}
catch
{
//关闭连接
conn.Close();
conn.Dispose();
//向上抛异常，表示需要获取的数据出现异常，并且提示出错信息
throw;
}
}
}
private void button1_Click(object sender, EventArgs e)
{
string sql = "select count(*) from classtable where classId=@uid and class=@pwd";
SqlParameter[] pms = new SqlParameter[]{
new SqlParameter("@uid",SqlDbType.Int){Value=textBox1.Text.Trim()},
new SqlParameter("@pwd",SqlDbType.VarChar,50){Value=textBox2.Text}
};
int r=(int) SqlHelper.Form1.ExecuteScalar(sql, pms);
if (r > 0)
{
MessageBox.Show("登陆成功");
}
else
{
MessageBox.Show("登陆失败");
}
}
//使用ExecuteReader读取数据
private void button3_Click(object sender, EventArgs e)
{
List<TblClass> list=new List<TblClass>();
string sql = "select * from classtable";
using (SqlDataReader reader = SqlHelper.Form1.ExecuteReader(sql))
{
if (reader.HasRows)
{
while (reader.Read())
{
TblClass model = new TblClass();
model.classId = reader.GetInt32(0);
model.class1 = reader.GetString(1);
model.classname = reader.IsDBNull(2) ? null : reader.GetString(2);
list.Add(model);
}
}
MessageBox.Show(list.Count.ToString());
}
}
}
}