Solution Guide for Migrating Oracle on UNIX to SQL Server - Willy .Net

286 Developing: Applications — <strong>Migrating</strong> <strong>Oracle</strong> FormsFigure 17.5 shows the different components that make up a master-detail block ascreated by the Data Block Wizard.Figure 17.5Code generated by <strong>Oracle</strong> Forms Builder Data Block Wizard in creating a master-detail blockBy capturing a query on a table, a block can also be designed to show one or morerecords at a time. These are called single-record blocks or multi-record blocks,respectively.Visual Basic .NET developers can use <strong>Oracle</strong> Forms Builder to look at the generatedcode to find out about the relationships between the blocks. For example, in Figure 17. 5,code in the ON-POPULATE-DETAILS trigger on the DEPT block suggests that it is themaster block of the EMP block.In Visual Basic .NET, the equivalent of an <strong>Oracle</strong> Form data block is a Dataset into whichdata can be read from the database, and on the visual side, a DataGrid control bound tothe Dataset will be capable to display the data. Dataset is just one option. In addition tothe Dataset, ADO.NET offers DataReader <strong>for</strong> read-only data access.Additional properties convey the association between a data block and a table, such asthe WHERE clause and ORDER BY clause that will be used to create SQL <strong>for</strong> theVisual Basic .NET Dataset. The Insert Allowed, Update Allowed, and Delete Allowedproperties will tell the Visual Basic .NET developer whether the block will insert, update,or delete any records.