Working with designers
- 2. Connection StringStored in app.config (XML file)Connection string with a local database specifies a |DATA| directory
- 3. Database file is copied from project folder to bin folder when run projectSchema FileXSD file uses XML to define dataset contents
- 4. Form Contentsdataset manages data in memorytable adapter manages the requests for data (both in/out of db)Can include multiple SELECT statementstable adapter manager controls how to manage data changes to table and related tablesIn relational database order of edits matters
- 5. Form Contents - 2data grid view provides on screen display of data Includes built in tools – sorting, adjusting tablebinding navigator manages navigation of rows/editingbinding source connects form/controls to data setServes as “glue” to make sure the contents of each field in each row properly displayed in controls
- 6. BindingComplex data binding happens when dealing with rows and columns (grid, list controls)Simple data binding is for a control connected to a single column
- 7. Reading/Writing DataGetting data: Table adapter (or data adapter) has a FILL method that executes the SELECT statementAn argument specifies where the data should end up in memorySaving data: Table adapter (or data adapter) has an UPDATE methodTable adapter manager has an UPDATE ALL that manages the execution of updates to related tables
- 8. Reading/Writing Data - 2Ensure that all validation is done (Me.Validate) Ensure that no editing is going on before use Update (bindingsource.EndEdit)Referential integrity means order matters
- 9. ExceptionsHave exception classes for each data provider (SQL Server, Oracle, OLEDB, ODBC)Reading the Number property of SQL Server exception objects refers to the specific error from SQL ServerTypical exceptions in ADO.Netnot provider basedDB Concurrency - row in table is different that the original version (optimistic concurrency)Data Exception - generic exception from providerConstraint Exception violates validation rulesNo null allowed - required field is missing a value
- 10. Data Grid ExceptionsData grid can generate exceptionsValue in cell doesn't match requirements in data column (Null, invalid type)Can find the location of an exception by Row and Column (index values)
- 11. Refreshing DataAfter 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