public int ExecuteSql(string sql, out string errText)
    {
        try
        {
            errText = string.Empty;
            DbCommand cmd = DBcnn.CreateCommand();
             = CommandType.Text;
             = sql;
            return cmd.ExecuteNonQuery();
        }
        catch (System.Exception e)
        {
            errText = e.Message;
            return -1;
        }

    }
下面是调用
public bool selectByEmail(string email)
    {
        int rs;
        string sql = "select count(*) from EcrdAccount where email="+email;
        rs = sqlHelper.ExecuteSql(sql,  ??? );//这里怎么写?
        return rs > 0;
    }

out string errText 是什么意思?

为什么要加out ,有什么好处?

好象是抛出什么错误信息?
就是不太明白,直接根据返回值判断不也可以吗?

这种写发有什么好处?