c# - DataAdapter: Update unable to find TableMapping['Table'] or DataTable 'Table' -


this code snippet throwing error:

update unable find tablemapping['table'] or datatable 'table'.) on adapter.update(ds); line

why throwing type of error?

sqlconnection con = new sqlconnection(); con.connectionstring = connectionstring();  dataset ds = new dataset();  string strquery = "select * cars"; sqldataadapter adapter = new sqldataadapter();  adapter.selectcommand = new sqlcommand(strquery, con);  sqlcommandbuilder builder = new sqlcommandbuilder(adapter);  adapter.fill(ds, "cars");  //code modify data in dataset ds.tables["cars"].rows[0]["brand"] = "newbrand";  adapter.updatecommand = builder.getupdatecommand(); adapter.update(ds);

use 

adapter.update(ds, "cars");

instead.

i have tested it. got same error without , works if specify tablename. however, must admit yet don't know why dataadapter needs know table-name since has informations needs. if useds.getchanges 1 row correct table-name.

update have found nothing on msdn found in source(ilspy). here implementation of dbdataadapter.update(dataset):

public override int update(dataset dataset) {     return this.update(dataset, "table"); }

so if don't specify table, table-name "table" used , if you've specified table-name other you'll error, that's strange!

i assume reason dataadapter cannot call getchanges determine table update 2 reasons:

  1. it inefficient since needs loop tables , of rows find rows rowstate != unchanged
  2. it's possible multiple tables needs updated since contain changed rows. not supported via dataadapter. hence dataadapter.update(dataset) assumes default name "table" table-name.

edit: however, maybe can explain me why dataadapter doesn't use dataset.tables[0].tablename instead.

so in general seems best practise specify name of table want update.


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