to be aware of the two main types of triggers; these are Row and Statement level triggers. The distinction between the two is how many times the code within the trigger is executed, and at what time. Suppose you have a trigger that is made to be called on an UPDATE to a certain table. Row level triggers would execute once for each row that is affected by the UPDATE. It is important to keep in mind if no rows are affected by the UPDATE command, the trigger will not execute any code within the trigger. Statement level triggers will be called once regardless of how many rows are affected by the UPDATE. Here it is important to note that even if the UPDATE command didn't affect any rows, the code within the trigger will still be executed once. Using the BEFORE and AFTER options determine when the trigger is called. Suppose you have a trigger that is called on an INSERT to a certain table. If your trigger is using the BEFORE option, the code within the trigger will be executed before the INSERT into the table occurs. A common use of the BEFORE trigger is to verify the input values of the INSERT, or modify the values accordingly. Now let's say we have a trigger that uses AFTER instead. The code within the trigger is executed after the INSERT happens to the table. An example use of this trigger is creating an audit history of who has made inserts into the database, keeping track of the changes made. When using these options you need to keep a few things in mind. The BEFORE option does not allow you to modify tables, that is why input validation is a practical use. Using AFTER triggers allows you to modify tables such as inserting into an audit history table. When creating a trigger to determine if it is statement or row level simply include the FOR EACH ROW clause for a row level, or omit the clause for a statement level. Be cautious of using additional INSERT/UPDATE/DELETE commands within your trigger, because trigger recursion is possible, causing unwanted behavior. In the examples below each trigger is modifying a different table, by looking at what is being modified you can see some common applications of when different trigger types are used. The following is an Oracle syntax example of a row level