Trigger updating - Online sex
In this article I want to show how to use an UPDATE and DELETE trigger and introduce INSTEAD OF triggers.If you are not familiar with the inserted and deleted tables please read this article before continuing. Ord_Priority for orders with a priority of 'High.' The UPDATE trigger watches for orders whose priority are changed from something else to High.
A variety of SQL statements are legal inside the Trigger body, though.A few months ago I wrote an article for SQLTeam called An Introduction to Triggers -- Part I.The article covered trigger fundamentals--the most important being the way the inserted and deleted virtual tables work.I also showed an example of how to use an INSERT trigger to log activity on a web site.In other words, the old row and the new row are simply destroyed and you're left with the same thing you started with: the actual row.The Trigger action defines the SQL statements you want the Trigger to execute when it is activated and has three parts: the action granularity, the action when condition and the action body.
The optional statement defines the Trigger action itself: the SQL statement(s) you want your DBMS to execute when the Trigger is activated.
The action body may be either a single SQL statement or it may be a series of SQL statements, delimited by semicolons, with a that is an SQL- transaction statement, an SQL-Connection statement, an SQL-Schema statement or an SQL-session statement (see chapter 1, SQL statement classes).
The authors have graciously allowed us to reproduce the contents of the book here. Triggers will be activated whenever you execute the appropriate SQL data-change statement on the Table, whether you want them or not.) The Trigger action time defines when you want the Trigger's action to be executed: it may be either if you want the Trigger action to occur after the Trigger event.
Because the book is about the SQL-99 standard, the contents of this and other pages in the book may not directly apply to Maria DB. statement's main parts are its Table, its event (the description of the SQL-data change statement that activates the Trigger) and its action (the SQL statements which are to be executed by the Trigger). The Trigger event defines the SQL-data change statement whose execution (on the Trigger's Table) will activate the Trigger: it may be either on Columns not in the list won't activate the Trigger).
The Column list names some or all of the Trigger Table's Columns (each may appear in the list only once).
If you omit this optional subclause, the effect is as if you included an s, or aliases: one name for the old row acted on by the Trigger and/or one name for the new row acted on by the Trigger and/or one name for the old Table acted on by the Trigger and/or one name for the new Table acted on by the Trigger (each may be specified once). The execution context is "atomic" in the usual SQL sense of the word: if any action statements fail, then all action statements fail and so does the statement that caused the Trigger activation: your DBMS will return the .