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Oracle Database SQL Certified Associate

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Interview Questions and Answers

A trigger is an automatic action executed in response to a specific event on a table, such as INSERT, UPDATE, or DELETE.

EXISTS checks for the existence of rows, while IN checks if a value exists within a given set.

A self-join is a join in which a table is joined with itself.

A subquery is a query inside another SQL query that returns a single value or a set of rows.

Views are virtual tables based on SQL queries that allow data abstraction and security.

CHAR stores fixed-length strings, while VARCHAR stores variable-length strings.

DELETE removes specific rows and logs the operation, whereas TRUNCATE removes all rows without logging each row deletion.

GROUP BY groups rows that have the same values in specified columns and applies aggregate functions.

ACID stands for Atomicity, Consistency, Isolation, and Durability, ensuring reliable transactions in a database.

A stored procedure is a precompiled collection of SQL statements stored in the database for reuse.

UNION removes duplicate rows, whereas UNION ALL includes all rows, including duplicates.

A foreign key is a column that establishes a relationship between two tables by referencing the primary key of another table.

Normalization is the process of structuring a relational database to reduce redundancy and improve data integrity.

Indexes improve the speed of data retrieval operations in a database by reducing the number of required scans.

INNER JOIN returns only matching rows from both tables, whereas LEFT JOIN returns all rows from the left table and matching rows from the right table.

WHERE filters rows before aggregation, while HAVING filters groups after aggregation.

SQL commands are categorized into DDL (Data Definition Language), DML (Data Manipulation Language), DCL (Data Control Language), and TCL (Transaction Control Language).

SQL is a query language, whereas MySQL is a relational database management system (RDBMS) that uses SQL to manage databases.

A primary key is a column (or a set of columns) that uniquely identifies each row in a table.

SQL (Structured Query Language) is a standard language for managing and manipulating relational databases.