C# 数据库连接必备(SqlHelper)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Configuration;
using System.Data.SqlClient;
using System.Data;

/// <summary>
///SqlHelper 的摘要说明
/// </summary>
public class SqlHelper
{
    public SqlHelper()
    {
        //
        //TODO: 在此处添加构造函数逻辑
        //
    }
    public static object ExecuteScalar(string sql, params SqlParameter[] para)
    {
        string connStr = ConfigurationManager.ConnectionStrings["connChat"].ConnectionString;
        SqlConnection conn = new SqlConnection(connStr);
        SqlCommand comm = new SqlCommand(sql, conn);
        comm.Parameters.AddRange(para);
        object ans;
        conn.Open();
        ans = comm.ExecuteScalar();
        conn.Close();
        return ans;
    }

    public static void ExecuteNonQuery(string sql, params SqlParameter[] para)
    {
        string connStr = ConfigurationManager.ConnectionStrings["connChat"].ConnectionString;
        SqlConnection conn = new SqlConnection(connStr);
        SqlCommand comm = new SqlCommand(sql, conn);
        comm.Parameters.AddRange(para);
        conn.Open();
        comm.ExecuteNonQuery();
        conn.Close();
    }

    public static SqlDataReader GetDateReader(string sql, params SqlParameter[] para)
    {
        string connStr = ConfigurationManager.ConnectionStrings["connChat"].ConnectionString;
        SqlConnection conn = new SqlConnection(connStr);
        SqlCommand comm = new SqlCommand(sql, conn);
        comm.Parameters.AddRange(para);
        conn.Open();
        return comm.ExecuteReader();
    }
    public static DataTable GetDataTable(string sql, params SqlParameter[] para)
    {
        string connStr = ConfigurationManager.ConnectionStrings["connChat"].ConnectionString;
        using (SqlConnection conn = new SqlConnection(connStr))
        {
            SqlDataAdapter sda = new SqlDataAdapter(sql, conn);
            DataTable dt = new DataTable();
            sda.SelectCommand.Parameters.AddRange(para);
            sda.Fill(dt);
            return dt;
        }
    }
}using System;
using System.Collections.Generic;