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.NET Forum / Languages / C# / January 2008use DataAdpater fill datatable couple times for many columns
Hi, If I have a very big view in database, it covers 15 tables, each table has 1000 columns. When I issue select * from view, the database will give error -- too many columns. Can I use a DataAdapter fill DataTable couple times? For example, I only read 5000 columns from the view each time and I read 3 times. It has an id column as primary key to help locate the row. How to write a DataAdapter to fill DataTable 3 times? What is the most efficient way to do this? Thanks a lot! ~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~. Ryan Liu Shanghai Fengpu Software Co. Ltd Shanghai , China http://www.PowerCATI.com Powerful CATI! http://www.fpsoft.net.cn ~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~. > If I have a very big view in database, it covers 15 tables, each table has > 1000 columns. [quoted text clipped - 8 lines] > How to write a DataAdapter to fill DataTable 3 times? What is the most > efficient way to do this? If you try to use a DataAdapter to fill the table three times, it will attempt to add additional rows to the DataTable, rather than adding new columns to the existing rows. Instead of the DataAdapter, use a DataReader. Loop through the rows returned by the datareader and add their data into the additional columns in the datatable. You will have to create the columns beforehand in the table (you can also do this with a looping construct). These loops take more work to program than just using a DataAdapter, but they are equally efficient, since it is what the dataadapter does internally anyway. >> If I have a very big view in database, it covers 15 tables, each table >> has 1000 columns. [quoted text clipped - 18 lines] > more work to program than just using a DataAdapter, but they are equally > efficient, since it is what the dataadapter does internally anyway. Then what about I use a few DataAdapter fill a few DataTalbe and then merge DataTables? Thanks! > Then what about I use a few DataAdapter fill a few DataTalbe and then > merge DataTables? I have not tried it out, but from the documentation of the Merge method it appears that it may work, as long as you use the overload of Merge that takes a MissingSchemaAction parameter and you specify the value MissingSchemaAction.Add.
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