DATABASE 和 DATATABLE 之间的重复检查 [英] Duplicacy check between DATABASE and DATATABLE

问题描述

我的数据库中有一个名为 PNUMSET(主键)的列包含唯一数据.(大约 1L 行)

i have one column in my database by name PNUMSET (Primary Key) contains unique data.(approx 1L rows)

在应用程序中，我有一个包含数据的列名 NEWPNUM 的数据表.

and in application i have one datatable with one column name NEWPNUM which contains data.

我想检查现有数据库和当前数据表值之间是否没有匹配的值..

i want to check that no value is matching between existing database and current datatable values..

注意:- 数据库和数据表中的行数可能相同也可能不同.

Note:- no of rows may or may not be same in database and datatable.

到目前为止我尝试过.....

so far i tried.....

           String query = "Select PNUMSET FROM DUMMYTABLE";
           MySqlDataAdapter msda = new MySqlDataAdapter(query, connection);
           msda.Fill(dt);                

            for (int k = 0; k < Class1.global_dataset.Tables[0].Rows.Count; k++)
            {
                if (dt.Rows.Contains(Class1.global_dataset.Tables[0].Rows[k][4].ToString()))
                {
                    MessageBox.Show("Baj Gaya Ghanta!!!!");
                }
            }

推荐答案

您可以使用 Linq-To-DataTable 来加入这列上的两个表，例如:

You can use Linq-To-DataTable to join both tables on this column, for example:

var commonRows = from r1 in dt.AsEnumerable()
                 join r2 in Class1.global_dataset.Tables[0].AsEnumerable()
                 on r1.Field<int>(4) equals r2.Field<int>(4)
                 select r1;
if(commonRows.Any())
{
    // do something with these rows
}

(假设第 5 列是 int)

(assuming the 5th column and it's type int)

请注意，虽然 Enumerable.Join 非常有效，最好在数据库中进行比较，而不是将所有内容加载到内存中.

Note that although Enumerable.Join is quite efficient it might be better to compare this in the database instead of loading all into memory.

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