基礎程式碼

private void btnLogin_Click(object sender, EventArgs e)
{
    string uid = txtUserName.Text.Trim();
    string pwd = txtPwd.Text.Trim();
    SqlParameter[] spa = new SqlParameter[]{
        new SqlParameter("@uid",uid),
        new SqlParameter("@pwd",pwd)
    };
    string sql = "select * from Login where 
 
[email protected] And [email protected]";
    string result = SqlHelper.ExecuteDataTable(sql, spa).Rows.Count.ToString();
    if (Convert.ToInt32(result)>0)
    {
        MessageBox.Show("登入成功！");
    }
    else
    {
        MessageBox.Show("登入失敗！");
    }
}

SQLHelper

class SqlHelper
{
    //wf專案中，請新增對System.Configuration的引用
 

    //1.對配置檔案connectionStrings節進行讀取
    static string connstr = System.Configuration.ConfigurationManager.ConnectionStrings["connStr"].ConnectionString;

    /// <summary>
    /// 查詢資料庫返回一張表
    /// </summary>
    /// <param name="sql">查詢字串</param>
    /// <param name="parameters">查詢所需要的引數</param>
 

    /// <returns>返回查詢的結果的第一個結果集的表</returns>
    public static DataTable ExecuteDataTable(string sql, params SqlParameter[] parameters)
    {
        //建立一個臨時的資料集，在記憶體裡
        DataSet ds = new DataSet();
        //建立一個介面卡物件
        SqlDataAdapter adapter = new SqlDataAdapter(sql, connstr);
        //給介面卡物件的查詢命令物件新增引數
        adapter.SelectCommand.Parameters.AddRange(parameters);
        try
        {
            //填充資料集
            adapter.Fill(ds);
            return ds.Tables[0];
        }
        catch (Exception) //如果捕捉錯誤就返回null
        {
            return null;
        }
    }

    /// <summary>
    /// 資料庫的增刪改語句
    /// </summary>
    /// <param name="sql">sql語句</param>
    /// <param name="parameters">引數</param>
    /// <returns></returns>
    public static int ExecuteNonQuery(string sql, params SqlParameter[] parameters)
    {
        using (SqlConnection conn = new SqlConnection(connstr))
        {
            using (SqlCommand cmd = new SqlCommand(sql, conn))
            {
                cmd.Parameters.AddRange(parameters);
                conn.Open();
                return cmd.ExecuteNonQuery();
            }
        }
    }

    /// <summary>
    /// 查詢返回單個的值
    /// </summary>
    /// <param name="sql">sql語句</param>
    /// <param name="parameters">引數</param>
    /// <returns>首行首列的值</returns>
    public static object ExecuteScalar(string sql, params SqlParameter[] parameters)
    {
        using (SqlConnection conn = new SqlConnection(connstr))
        {
            using (SqlCommand cmd = new SqlCommand(sql, conn))
            {
                cmd.Parameters.AddRange(parameters);
                conn.Open();
                return cmd.ExecuteScalar();
            }
        }
    }
}

配置檔案

<configuration>
  <connectionStrings>
    <add name="connStr" connectionString="server=.;database=Test;uid=sa;pwd=jujianfei"/>
  </connectionStrings>
</configuration>