What is a trigger and how does it work?
Theme: Database Programming Role: Database Administrator Function: Technology
Interview Question for Database Administrator: See sample answers, motivations & red flags for this common interview question. About Database Administrator: Manages and optimizes databases for efficient data storage and retrieval. This role falls within the Technology function of a firm. See other interview questions & further information for this role here
Sample Answer
Example response for question delving into Database Programming with the key points that need to be covered in an effective response. Customize this to your own experience with concrete examples and evidence
- Definition of a trigger: A trigger is a database object that is associated with a table and automatically executes a set of actions when a specific event occurs on that table
- Types of triggers: There are two types of triggers: 1) DML triggers, which are fired in response to data manipulation language (DML) statements like INSERT, UPDATE, or DELETE; and 2) DDL triggers, which are fired in response to data definition language (DDL) statements like CREATE, ALTER, or DROP
- Trigger components: A trigger consists of three main components: 1) the triggering event, which specifies the action that causes the trigger to fire; 2) the trigger action, which defines the set of actions to be executed when the trigger fires; and 3) the trigger timing, which determines whether the trigger fires before or after the triggering event
- Trigger execution: When a triggering event occurs, the trigger is automatically executed. The trigger action can include SQL statements, stored procedures, or even calls to external programs. The trigger can access and modify data in the table on which it is defined, as well as perform additional actions based on the specific requirements
- Benefits of triggers: Triggers provide several benefits, including: 1) enforcing data integrity by validating or modifying data before it is inserted, updated, or deleted; 2) automating repetitive tasks or complex business logic; 3) auditing changes to the data by capturing information about the triggering event; and 4) maintaining referential integrity by automatically updating related tables when changes occur in the parent table
- Considerations for using triggers: While triggers can be powerful tools, they should be used judiciously due to potential performance implications. It is important to carefully design triggers to minimize their impact on database performance and ensure they do not introduce unintended side effects. Additionally, triggers should be thoroughly tested and documented to ensure their reliability and maintainability
Underlying Motivations
What the Interviewer is trying to find out about you and your experiences through this question
- Knowledge of database concepts: Understanding of triggers and their functionality in a database system
- Problem-solving skills: Ability to identify and implement triggers to automate actions based on specific conditions
- Experience with database administration: Hands-on experience in creating, modifying, and managing triggers in database systems
- Attention to detail: Understanding the syntax and structure of triggers to ensure accuracy and avoid errors
Potential Minefields
How to avoid some common minefields when answering this question in order to not raise any red flags
- Lack of understanding: Providing a vague or incorrect definition of a trigger or how it works
- Inability to provide examples: Not being able to explain real-life scenarios where triggers are useful
- Limited knowledge: Not being aware of different types of triggers or their syntax in the specific database management system being used
- Poor problem-solving skills: Struggling to explain how triggers can be used to solve specific database-related issues or improve performance