>Actually we do that way wherein we assume the size co datatype base on how they create. But the problem is we have some datatype with different size. Example sometimes the default value of nVarChar = 50, but there was a case like in "comment" we make it more than to that value. Regarding GetSchemaTable, im not familiar to used that. Can u give me some example of using that in datagrid wherein we can update, insert, and delete direct to the grid..
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>If you have some tips of making parameters in datagrid except using commandbuilder, (we have a complex datatable) please send it to me. It will help me a lot. Thank you. Good day

GetSchemaTable is not a part of the DataGrid. It is a method of the OleDbDataReader that returns a new DataTable containing the names, data types, lengths, etc.. of the columns in the base table. If you haven't used it before, I suggest reading over the documentation on it. The samples are clear and easy to integrate into your own code.

In VS2003 help, the link is

ms-help://MS.VSCC.2003/MS.MSDNQTR.2005JAN.1033/cpref/html/frlrfSystemDataOleDbOleDbDataReaderClassGetSchemaTableTopic.htm

Concerning the command builder, the only tip that will make any sense at this point is to start with a simple one-table dataset and work through the sample code in the help files. Once the relationship between DataAdapters, OleDbCommands, DataTables, and DataGrids become clear to you, the rest will fall into place.