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Working with designers

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Working with designers

  1. 1. Working With Designers<br />CIS-266<br />
  2. 2. Connection String<br />Stored in app.config (XML file)<br /><ul><li>Connection string with a local database specifies a |DATA| directory
  3. 3. Database file is copied from project folder to bin folder when run project</li></li></ul><li>Schema File<br />XSD file uses XML to define dataset contents<br />
  4. 4. Form Contents<br />dataset manages data in memory<br />table adapter manages the requests for data (both in/out of db)<br />Can include multiple SELECT statements<br />table adapter manager controls how to manage data changes to table and related tables<br />In relational database order of edits matters<br />
  5. 5. Form Contents - 2<br />data grid view provides on screen display of data <br />Includes built in tools – sorting, adjusting table<br />binding navigator manages navigation of rows/editing<br />binding source connects form/controls to data set<br />Serves as “glue” to make sure the contents of each field in each row properly displayed in controls<br />
  6. 6. Binding<br />Complex data binding happens when dealing with rows and columns (grid, list controls)<br />Simple data binding is for a control connected to a single column<br />
  7. 7. Reading/Writing Data<br />Getting data: Table adapter (or data adapter) has a FILL method that executes the SELECT statement<br />An argument specifies where the data should end up in memory<br />Saving data: <br />Table adapter (or data adapter) has an UPDATE method<br />Table adapter manager has an UPDATE ALL that manages the execution of updates to related tables <br />
  8. 8. Reading/Writing Data - 2<br />Ensure that all validation is done (Me.Validate) <br />Ensure that no editing is going on before use Update (bindingsource.EndEdit)<br />Referential integrity means order matters<br />
  9. 9. Exceptions<br />Have exception classes for each data provider (SQL Server, Oracle, OLEDB, ODBC)<br />Reading the Number property of SQL Server exception objects refers to the specific error from SQL Server<br />Typical exceptions in ADO.Net<br />not provider based<br />DB Concurrency - row in table is different that the original version (optimistic concurrency)<br />Data Exception - generic exception from provider<br />Constraint Exception violates validation rules<br />No null allowed - required field is missing a value<br />
  10. 10. Data Grid Exceptions<br />Data grid can generate exceptions<br />Value in cell doesn't match requirements in data column (Null, invalid type)<br />Can find the location of an exception by Row and Column (index values)<br />
  11. 11. Refreshing Data<br />After save data, may want to "refresh" the dataset - make sure what's in memory is same as what was saved, especially when have identity columns<br />

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