Updating relational databases through views

posted by | Leave a comment

Read this section if you are new to Access or unfamiliar with the concepts behind relational databases.

updating relational databases through views-37updating relational databases through views-6updating relational databases through views-55

For example, in 1996 the Baltimore Oriole was recognized as a separate species.In a relational database system, this would be managed by adding a single entry to the table for the genus Icterus.From a practical standpoint, what this means is that the task of classification now has the absolute minimum of complexity — one species: one table entry — and all uses of that information automatically follow.Here is one of the triggers that call the above code (the triggers are virtually identical): CREATE TRIGGER `before_update_invoice` before update ON `invoice` for each row BEGIN call proc_process_invoice( new.salesperson_id, new.inventory_id, new.quantity, new.in_stock, new.remain, new.price, new.discount, new.pre_tax, new.tax, new.subtotal, new.comment); END| The point of calling a procedure from the trigger is that both triggers (for insert and update) need to do the same thing in the same way, so they call a common code block.In relational databases more than anywhere else, the value of views become clear — the invoice view (Figure 7) can access a table like the invoice, linked by foreign keys to the other two tables but bereft of most information in text form, and acquire the text representations of various quantities that only appear as indices in the invoice table.

Leave a Reply

  1. dating lines phone 05-Jan-2020 12:07

    It will benefit all of your relationships, ministry, career, and potential marriage.

  2. pretty fish dating site 01-Oct-2019 18:52

    You don't have to be completely alone, so reach out and take advantage of the resources around you.

  3. Pornochat publik 11-Nov-2019 05:08

    Timberlake once dated fellow pop singer Britney Spears and actress Cameron Diaz. After an on-and-off relationship that lasted several years, the couple got married in October of 2012, in Puglia, Italy.

Free online hot sex chat sighs