DBMS Basics Practice Test: SQL - Queries, Constraints and Triggers — Flashcards

Quiz questions on SQL basics, set and null value operations, database modifications, views and transactions, different types of integrity constraints, joins, nested subqueries and aggregate functions, schemas and data types, triggers, functions and procedures and different queries and aggregation features.

SQL queries are commands that retrieve data from a database, and are similar to questions a user asks a database. SQL constraints are rules that limit the data in a table to meet certain regulations. SQL triggers are database objects that execute SQL statements when a specific event occurs on a table. Triggers are used to enforce business rules, maintain data integrity, and automate database actions. 

Here are some types of SQL constraints and triggers:
Integrity constraints: Rules that limit the data in a table to meet certain regulations. For example, SQL Server uses referential integrity constraints to ensure that data in one table points to data in another table.
Declarative integrity constraints: Statements about the database that are always true.
DML triggers: Run when a user tries to modify data through a data manipulation language (DML) event, such as INSERT, UPDATE, or DELETE statements on a table or view.
Logon triggers: Fire after a successful logon.
BEFORE INSERT triggers: Can be used to check if the column values to be inserted are valid. 

Triggers can supplement the built-in auditing features of Oracle. However, triggers should only be used when more detailed audit information is required.