In the above example, all the triggers that are present in the database named Edureka will be displayed. The below code will display all the triggers that are present in a particular database. The below code will display all the triggers that are present. Some may be simple and some may be a little complex, but once if we go through the query its easy to understand. We can perform many operations using triggers. Here the “ NEW” keyword refers to the row that is getting affected. In the below trigger, we are trying to calculate the percentage of the student as soon as his details are updated to the database. So that was all about the syntax of triggers, lets now try to implement an example of triggers in SQL. Now, what if he wishes to keep track of the number of customers to whom the email was sent? Now John needs to create a nested trigger to keep the track of the count along with sending an email. Continuing from the earlier scenario, John sent an email for every new customer that was added to the company’s database. Rather than giving you a tailored answer let me share a scenario with you, which will help you in understanding the nested trigger in a better way. You might be wondering in which scenario we can use the nested trigger. If we don’t end the trigger properly it may lead to an infinite loop. Also h andling it and terminating it at the right time is very important. But we can also create a nested trigger that can do multi-process. It consists of queries that need to be executed when the trigger is called. Column Level Trigger gets executed before or after the specified column changes.Row-level trigger gets executed before or after any column value of a row changes.Don’t forget to use on keyword and also make sure the selected table is present in the database. We need to mention the table name on which the trigger is being applied. These are the DML operations and we can use either of them in a given trigger. We cannot use After trigger if we want to update a record because it will lead to read-only error. The records that activate the after trigger are read-only. After Triggers are used to access field values that are set by the system and to effect changes in other records. ![]()
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