C#，一份超简单的数据库帮助类，SqlHelp

简单，实用，留存。

 using System;
 using System.Collections.Generic;
 using System.Configuration;
 using System.Data;
 using System.Data.SqlClient;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
 
 namespace CarHailing.Base
 {
     /// <summary>
     ///  数据库帮助类
     /// </summary>
     public class SqlHelp
     {
         /// <summary>
         /// 创建一个已打开的连接
         /// </summary>
         /// <returns></returns>
         private static SqlConnection CreateConn()
         {
             SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["conn"].ConnectionString);
             conn.Open();
             return conn;
         }
 
         /// <summary>
         /// 执行sql语句，返回受影响的行数
         /// </summary>
         /// <param name="sql"></param>
         /// <returns></returns>
         public static int ExecuteNonQuery(string sql)
         {
             return ExecuteNonQuery(sql, null);
         }
 
         /// <summary>
         /// 执行sql语句，返回受影响的行数
         /// </summary>
         /// <param name="sql"></param>
         /// <returns></returns>
         public static int ExecuteNonQuery(string sql, SqlParameter[] ps)
         {
             SqlConnection conn = CreateConn();
             SqlCommand cmd = new SqlCommand(sql, conn);
             try
             {
                 if (ps != null)
                 {
                     cmd.Parameters.AddRange(ps);
                 }
                 return cmd.ExecuteNonQuery();
             }
             catch (Exception ex)
             {
                 return ;
             }
             finally
             {
                 conn.Close();
             }
         }
 
         /// <summary>
         /// 执行sql语句,返回一个结果表
         /// </summary>
         /// <param name="sql"></param>
         /// <returns></returns>
         public static DataTable ExecuteSelectDataTable(string sql)
         {
             return ExecuteSelectDataTable(sql, null);
         }
 
         /// <summary>
         /// 执行sql语句,返回一个结果表
         /// </summary>
         /// <param name="sql"></param>
         /// <param name="ps"></param>
         /// <returns></returns>
         public static DataTable ExecuteSelectDataTable(string sql, SqlParameter[] ps = null)
         {
 
             SqlConnection conn = CreateConn();
             SqlCommand cmd = new SqlCommand(sql, conn);
             try
             {
                 if (ps != null)
                 {
                     cmd.Parameters.AddRange(ps);
                 }
                 //SqlDataAdapter sda = new SqlDataAdapter(cmd);
                 SqlDataReader read = cmd.ExecuteReader();
                 DataTable table = new DataTable();
                 table.Load(read);
                 //DataSet ds = new DataSet();
                 //sda.Fill(ds);
                 return table;
             }
             finally
             {
                 conn.Close();
             }
         }
 
         /// <summary>
         ///
         /// </summary>
         /// <param name="sql"></param>
         /// <returns></returns>decimal
         public static DataTable ExecuteSelectPageDataTable(string sql, ref SqlParameter[] ps)
         {
             SqlConnection conn = CreateConn();
             SqlCommand cmd = new SqlCommand(sql, conn);
             cmd.CommandType = CommandType.StoredProcedure;
             try
             {
                 cmd.Parameters.AddRange(ps);
                 SqlDataAdapter sda = new SqlDataAdapter(cmd);
                 DataSet ds = new DataSet();
                 sda.Fill(ds);
                 return ds.Tables[];
             }
             catch (SqlException ex)
             {
                 throw ex;
             }
             finally
             {
                 conn.Close();
             }
         }
 
         //public static SqlDataReader ExecuteReader(string cmdText, CommandType cmdType, params SqlParameter[] cmdParms)
         //{
         //    SqlCommand cmd = new SqlCommand();
         //    SqlConnection conn = CreateConn();
 
         //    try
         //    {
         //        ProCommand(cmd, conn, cmdText, cmdType, cmdParms);
         //        SqlDataReader rdr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
         //        //cmd.Parameters.Clear();//放到这里，返回参数会被清空。
         //        return rdr;
         //    }
         //    catch
         //    {
         //        conn.Close();
         //        throw;
         //    }
         //}
 
         /// <summary>
         /// 分页读取数据
         /// </summary>
         /// <param name="query">select查询语句</param>
         /// <param name="pageSize">每页显示数据数</param>
         /// <param name="PageIndex">当前页码</param>
         /// <param name="dt">存储数据的DataTable实例</param>
         public static void PageDataTable(string query, int pageSize, int PageIndex, DataTable dt)
         {
             //读取数据的开始索引
             long startIndex = (PageIndex - ) * pageSize;
             //读取数据的结束索引
             long endIndex = PageIndex * pageSize - ;
             //DataReader读取的当前数据行的索引
             long readToIndex = -;
             using (SqlConnection conn = CreateConn())
             {
                 SqlCommand cmd = new SqlCommand(query, conn);
                 //conn.Open();
                 SqlDataReader dr = cmd.ExecuteReader();
                 //数据源中的列数
                 int cols = dr.VisibleFieldCount;
                 //构造DataTable结构
                 for (int i = ; i < cols; i++)
                 {
                     dt.Columns.Add(new DataColumn(dr.GetName(i), dr.GetFieldType(i)));
                 }
                 //读取数据，将数据一行一行添加到DataTable
                 while (dr.Read())
                 {
                     readToIndex++;
                     //当DataReader指针在开始索引和结束索引闭区间时才读取数据构造DataRow
                     //并添加到DataTable
                     if (readToIndex >= startIndex && readToIndex <= endIndex)
                     {
                         DataRow row = dt.NewRow();
                         for (int i = ; i < cols; i++)
                         {
                             row[i] = dr[i];
                         }
                         dt.Rows.Add(row);
                     }
                 }
                 dr.Close();
             }
         }
     }
 }