参考Datatable C＃更新SQL表的最佳方法

Question

I have a data table that contains an Id column. The Id Column matches My tables ID Column. i need to use this ids to set a single value to my sql table. But the data table structure is not the same as my table structure, ie

  Data Table                        Sql Table
____________      _______________________________________________
ID                ID    | col 1 | col2 | col3 | col4 |final value
1                 1     | a     | b    |c     |d     |N
2                 2     | x     | y    |z     |a     |N

The data table at any given time is going to have more than 500,000 entries.

My Question Are:

1) will it be faster to build the Update Statement in and Execute them in a parallel loop within one transaction as shown below:

Sqltrn = Sqlconn.BeginTransaction();
Parallel.For (0; Datatable.Rows.Count; i =>
    {
       SqlCmd.CommandText = BuildStatemet;
       SqlCmd.ExecuteNonQuery();
    });
SqlTrn.Commit();

And will the above method cause dead lock on my table?

or

2) Execute a single statement by building a contacted string from the dt tables as such:

Update MyTable set  FinalValue = 'Y' WHERE ID in (CreateConcactedStringHere)

Which method is faster and safer, since i need to complete the updation in the least time possible and also avoid the table from locking since its a major transaction table in my database. Or is there any other way i can achieve this?

Answer 1

Individual rows update will be slower rather than a single update from a select. for this purpose I would recomment to

1. in your DB create a table like following TicketTable { TicketID, TargetID, SomePrecalculatedRes1, ..., SomePrecalculatedResN}
2. In C# create a DataTable object whith the same structure as the table from above
3. Fill the table content by data you will be using for your update. Each row has of the DataTable to have the same ticketId. (Parallel processing might give you some benifits)
4. Bulk insert the DataTable content into db.TicketTable (see SqlBulkCopy )
5. create an update command that takes in consideration your ticketId and updates your target table from a select from your ticket table