C#_DBHelper_SQL数据库操作类.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.Data.SqlClient;
using System.Windows.Forms;
 1 public class DBHelper
     {
         static string connStr = "Workstation id = localhost;" +
                                "Integrated Security = SSPI;" +
                                 "Database = 数据库名字;";//填入SQL数据库的登录信息。         static SqlConnection conn = new SqlConnection(connStr);         public static SqlDataReader GetDataReader(string sql)//返回值是一个数组，可通过dr[0],dr[1]使用各字段的值
         {
             SqlConnection myConn = conn;
             SqlDataReader dr = null;             try
             {
                 if (myConn.State == ConnectionState.Closed)
                 {
                     myConn.Open();
                 }
                 SqlCommand cmd = new SqlCommand(sql, myConn);                 dr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
             }
             catch
             {                 if (myConn.State == ConnectionState.Open)
                 {
                     myConn.Close();
                 }             }
             return dr;
         }         public static bool ExecuteNonQuery(string sql)  //对于 UPDATE、INSERT 和 DELETE 语句，返回值为该命令所影响的行数。对于所有其他类型的语句，返回值为 -1。如果发生回滚，返回值也为 -1
         {
             int n = ;             try
             {
                 if (conn.State == ConnectionState.Closed)
                 {
                     conn.Open();
                 }
                 SqlCommand cmd = new SqlCommand(sql, conn);
                 n = cmd.ExecuteNonQuery();             }
             catch
             {                 return false;
             }
             finally
             {
                 if (conn.State == ConnectionState.Open)
                 {
                     conn.Close();
                 }
             }
             return n > ;
         }         public static Object ExecuteScalar(string sql)//使用ExecuteScalar()，增删改查如果成功，会返回一个对象，否则会返回一个null；
         {
             Object ob = null;             try
             {
                 if (conn.State == ConnectionState.Closed)
                 {
                     conn.Open();
                 }
                 SqlCommand cmd = new SqlCommand(sql, conn);
                 ob = cmd.ExecuteScalar();
             }
             catch
             {
                 return null;
             }
             finally
             {
                 if (conn.State == ConnectionState.Open)
                 {
                     conn.Close();
                 }
             }
             return ob;
         }
     }
 }