You will probably use WRDB’s powerful features to naturally segregate your data into manageable units. For example, data will arrive in batches and can be kept in separate Working tables, each of which can be printed, graphed, etc. Furthermore, you may combine sets of similar Working tables (after validation) to form Master tables. You may even choose to create multiple Projects to further segregate your data.
Nevertheless, it is often helpful to perform operations on subsets of data contained in any of the tables described above. This makes it easier to interpret the data and reduces the time it takes to prepare reports and graphs.
As explained in Output Data Overview, selecting records is an essential part of reporting, graphing, and exporting data. Use one of four techniques for identifying what records you want to select for further processing:
The results from each of these operations places the selected data in a working table or view where it can very rapidly be processed further. WRDB keeps track of the source and contents of the working table. As long as you want to continue to work with that subset of data you don’t have to go through the time-consuming process of reselecting it. If you change to a different table, WRDB informs you that you must re-select the data subset before proceeding.