3i Infotech Senior Software Engineer Interview Questions and Answers

Nested table record types in PL/SQL allow complex data structures for efficient data handling.

• A nested table is a collection type that can hold an arbitrary number of elements.

• Syntax for creating a nested table type: `CREATE TYPE nested_table_type AS TABLE OF data_type;`

• To declare a variable of a nested table type: `DECLARE my_nested_table nested_table_type;`

• You can initialize a nested table using: `my_nested_table := ...read more

Triggers respond to database events; procedures are reusable code blocks; packages group related procedures/functions.

• Triggers are automatically executed in response to specific events (e.g., INSERT, UPDATE).

• Example of a trigger: A trigger that logs changes to a table whenever a row is updated.

• Procedures are named blocks of code that can be executed explicitly by calling them.

• Example of a procedure: A procedure that ca...read more

ACID properties ensure reliable transactions in databases: Atomicity, Consistency, Isolation, Durability.

• Atomicity: Transactions are all-or-nothing. Example: If a bank transfer fails, both accounts remain unchanged.

• Consistency: Transactions bring the database from one valid state to another. Example: A transaction must not violate any database rules.

• Isolation: Concurrent transactions do not affect each other. Example: ...read more

Cursors are database objects used to retrieve and manipulate data row by row.

• 1. Implicit Cursors: Automatically created by SQL for single SQL statements. Example: SELECT * FROM employees;

• 2. Explicit Cursors: Defined by the programmer for complex queries. Example: DECLARE cursor_name CURSOR FOR SELECT * FROM orders;

• 3. Forward-only Cursors: Can only move forward through the result set. Example: Used for simple read opera...read more