Question

我有一个表格，如下所示，我希望通过id得到记录，如果值b不存在则值为b，然后是值b。我在表格中有一个日期卷，我可以按日期使用订单。

我试图从移动设备发布屏幕图像，但是无法附加。也无法发布我试过的sql，因为这里是官方不允许的。

我试图解释这个问题在下面

Persid.      Value.    Date
1                 a
1                 a
1                 a
2                 b
2                 a
2                 a

预期结果

1           a.       Latest date
2           b        any date

我尝试在id和value列上使用group by来计算，但我无法理解如何使用该计数来过滤掉记录。

非常感谢任何帮助：）

Answer 1

您可以使用namespace i.model { public class CompanyRecords { public int? id { get; set; } public int? user_id { get; set; } public string product_name { get; set; } public string Keywords { get; set; } public string category { get; set; } public string description { get; set; } public string modules { get; set; } } [enter image description here][1]}：

 public List<CompanyRecords> GetProducts(string data,string idd, SearchModel searchSch)
    {   using (MySqlConnection conn = GetConnection())
        {
            conn.Open();
            List<CompanyRecords> results = conn.Query<CompanyRecords>("SELECT * FROM product WHERE category LIKE '%" + data + "%' OR Keywords LIKE '%" + data + "%' OR product_name LIKE '%" + data + "%' OR description LIKE '%" + data + "%' OR modules LIKE '%" + data + "%'OR metatags LIKE '%" + data + "%'OR geographical_focus LIKE '%" + data + "%'").ToList();

            //if (idd == "Category")
              if (!string.IsNullOrEmpty(searchSch.category))
            {
                //List<CompanyRecords> result = conn.Query<CompanyRecords>("SELECT * FROM product WHERE category LIKE '%" + data + "%'").ToList();


               List<CompanyRecords> result = conn.Query<CompanyRecords>(results.Where(x=>x.category.Contains(searchSch.category))).ToList();

                return result;
            }
            else if (idd == "Keywords")
            {
                List<CompanyRecords> result = conn.Query<CompanyRecords>("SELECT * FROM product WHERE Keywords LIKE '%" + data + "%'").ToList();
                return result;
            }
            else if (idd == "Modules") {
                List<CompanyRecords> result = conn.Query<CompanyRecords>("SELECT * FROM product WHERE modules LIKE '%" + data + "%'").ToList();
                return result;
            }
            return results;         
            //List<CompanyRecords> results = conn.Query<CompanyRecords>("SELECT * FROM product WHERE category LIKE '%" + data + "%'OR description LIKE '%" + data + "%' OR modules LIKE '%" + data + "%'OR metatags LIKE '%" + data + "%'OR geographical_focus LIKE '%" + data + "%'OR target_job_titles LIKE '%" + data + "%'OR target_industry_type LIKE '%" + data + "%'OR desktop_web_both LIKE '%" + data + "%'OR dept_user_type LIKE '%" + data + "%'OR semantic LIKE '%" + data + "%'OR cognitive LIKE '%" + data + "%'OR target_campany_size LIKE '%" + data + "%'").ToList();
            //if (results != null)
            //{ return results; }
            //return results;
        }  
    }

这将获取任何值的最新日期。请注意，row_number()是“b”出现在“a”之前。如果您的值不按字母顺序排序，则可以使用select id, value, date from (select t.*, row_number() over (partition by persid order by value desc, date desc ) as seqnum from t ) t where seqnum = 1;或其他机制来设置正确的排序顺序。

如果不是不同的，请选择不同的行或特定值行

1 个答案: