SqlHelper(基础)

using System; using System.Collections.Generic; using System.Data; using System.Data.SqlClient; using System.Linq; using System.Text; using System.Threading.Tasks;

namespace H.DAL {     /// <summary>     /// 数据库操作帮助类     /// 此段基础代码为SQLServer数据库帮助类     ///     如需操作MySQL     ///     1.将代码中Sql改为MySql     ///     2.添加MySql.Data.dll引用(可通过官网或NuGet)     ///     3.using System.Data.SqlClient;替换为using MySql.Data.MySqlClient;     /// </summary>     public class SQLHelper     {         /// <summary>         /// 数据库连接字符串         /// </summary>         private static string connectionStr = 　　　　　　　System.Configuration.ConfigurationManager.ConnectionStrings["dbConnection"].ConnectionString;         public SQLHelper() { }         public SQLHelper(string connectionStr)         {             SQLHelper.connectionStr = connectionStr;         }         /// <summary>         /// 得到连接对象         /// </summary>         /// <returns></returns>         public static SqlConnection GetConn()         {             SqlConnection sqlconn = null;             sqlconn = new SqlConnection(connectionStr);             return sqlconn;         }

/// <summary>         /// 查询操作         /// </summary>         /// <param name="sql"></param>         /// <returns></returns>         public static DataTable GetDataTable(string sql, params SqlParameter[] sp)         {             using (SqlConnection conn = GetConn())             {                 conn.Open();                 using (SqlDataAdapter sda = new SqlDataAdapter(sql, conn))                 {                     sda.SelectCommand.Parameters.AddRange(sp);                     DataTable dt = new DataTable();                     sda.Fill(dt);                     return dt;                 }             }         }         /// <summary>         /// 增删改操作         /// </summary>         /// <param name="sql">sql语句</param>         /// <returns>执行后的条数</returns>         public static int ExecuteNonQuery(string sql, params SqlParameter[] sp)         {             using (SqlConnection conn = GetConn())             {                 conn.Open();                 using (SqlCommand cmd = new SqlCommand(sql, conn))                 {                     cmd.Parameters.AddRange(sp);                     int i = cmd.ExecuteNonQuery();                     return i;                 }             }

}

/// <summary>         /// 执行一条SQL语句,返回首行首列         /// </summary>         /// <param name="sql">sql语句</param>         /// <returns>首行首列</returns>         public static object ExecuteScalar(string sql, params SqlParameter[] sp)         {             using (SqlConnection conn = GetConn())             {                 conn.Open();                 using (SqlCommand cmd = new SqlCommand(sql, conn))                 {                     cmd.Parameters.AddRange(sp);                     return cmd.ExecuteScalar();                 }             }         }     } }