PLSQL Relational Database Design: Chapter 1

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Questions and Answers

In PL/PgSQL, how do conditional statements contribute to controlling program flow?

Conditional statements allow the execution of specific code blocks based on whether a condition is true or false, thus directing the program's path.

What are the key differences between stored procedures and stored functions in PL/PgSQL?

Stored procedures can perform actions and do not necessarily return a value, while stored functions are designed to return a value and are often used in queries.

Explain how cursors are used in PL/PgSQL to handle result sets.

Cursors enable row-by-row access to the result set of a query, allowing for detailed processing of each record.

How are exceptions handled in PL/PgSQL, and why is it important for robust database applications?

Exceptions are handled using <code>BEGIN</code>, <code>EXCEPTION</code>, and <code>END</code> blocks to catch and manage errors, preventing application crashes and ensuring data integrity. Signup and view all the answers

What is the significance of using triggers in relational database design with PL/PgSQL?

Triggers enable automatic execution of specified actions in response to certain events on a table, such as inserts, updates, or deletes, enforcing business rules and data integrity. Signup and view all the answers

Describe the role of loops in controlling program flow within PL/PgSQL.

Loops are used to repeat a block of code multiple times, either for a fixed number of iterations or until a certain condition is met. Signup and view all the answers

Outline the basic structure of a PL/PgSQL code block.

A PL/PgSQL code block typically consists of a <code>DECLARE</code> section for variable declarations, a <code>BEGIN</code> section for the main code, and an optional <code>EXCEPTION</code> section for error handling. Signup and view all the answers

What are some common data types available in PL/PgSQL, and how do you decide which one to use for a particular variable?

Common data types include <code>INTEGER</code>, <code>TEXT</code>, <code>DATE</code>, and <code>BOOLEAN</code>. The choice depends on the type of data the variable will store. Signup and view all the answers

Explain the concept of in-built functions in PL/PgSQL and provide an example of how they simplify database operations.

In-built functions are pre-defined functions that offer common functionalities, such as string manipulation or date calculations, simplifying common database tasks. Example: <code>NOW()</code> to get the current timestamp. Signup and view all the answers

Describe a scenario where you would use a cursor instead of directly querying a table in PL/PgSQL. Explain why the cursor would be more appropriate in that situation.

When processing a large result set row-by-row to perform complex calculations or modifications, using a cursor is better due to its ability to fetch data iteratively, avoiding memory issues. Signup and view all the answers

Flashcards

What is PL/SQL?

An extension of SQL that combines procedural programming constructs, like loops and conditional statements, with SQL queries.

What are Stored Procedures?

Precompiled SQL code that can be stored in the database and executed by name.