Oracle SQL and PL/SQL Interview Question and Answers
Oracle SQL and PL/SQL Interview Question and Answers: Oracle SQL and PL/SQL are two essential components of the Oracle Database platform. SQL (Structured Query Language) is the standard language used to communicate with relational databases, and it is used to manipulate and query data stored in Oracle databases. PL/SQL (Procedural Language/Structured Query Language) is a powerful programming language that extends the functionality of SQL by providing the ability to write complex stored procedures, functions, and triggers.
In summary, Oracle SQL and PL/SQL are essential tools for developers and data analysts working with Oracle databases. SQL is used for data manipulation and querying, while PL/SQL is used to write complex procedures and functions that extend the functionality of SQL and provide additional business logic and data processing capabilities, Here we are Providing Important Oracle SQL and PL/SQL Interview Question and Answers.
Q: What is a primary key in Oracle SQL?
Answer: A primary key is a column or set of columns that uniquely identifies each row in a table. It ensures that no two rows can have the same values for the primary key columns.
Q: What is a foreign key in Oracle SQL?
Answer: A foreign key is a column or set of columns that references a primary key in another table. It is used to establish a relationship between two tables, and it ensures data integrity by preventing invalid data from being inserted into the referencing table.
Q: What is a stored procedure in PL/SQL?
Answer: A stored procedure is a named block of code that is stored in the database and can be executed multiple times. It can contain SQL statements, procedural logic, and input/output parameters.
Q: What is a cursor in PL/SQL?
Answer: A cursor is a mechanism used to traverse the records returned by a SQL query. It allows you to retrieve and process records one by one, and it provides finer control over the recordset than a simple SELECT statement.
Q: What is a trigger in PL/SQL?
Answer: A trigger is a named block of code that is automatically executed in response to certain events, such as INSERT, UPDATE, or DELETE operations on a table. It can be used to enforce business rules, maintain data integrity, or perform audit tracking.
Q: What is the difference between UNION and UNION ALL in Oracle SQL?
Answer: UNION and UNION ALL are used to combine the results of two or more SELECT statements. The main difference between them is that UNION removes duplicates from the result set, while UNION ALL includes all rows, even if they are duplicates.
Q: What is a sub query in Oracle SQL?
Answer: A sub query is a SELECT statement embedded within another SELECT statement. It is used to retrieve data that will be used in the main query, and it can be nested several levels deep.
Q: What is a view in Oracle SQL?
Answer: A view is a virtual table that is based on the result of a SELECT statement. It provides a way to simplify complex queries by creating a predefined set of columns and rows, and it can also be used to restrict access to sensitive data by granting permissions only to the view, not the underlying table.
These are just a few examples of the many question that might come up in an Oracle SQL and PL/SQL interview. It’s important to have a solid understanding of the fundamental concepts and syntax, as well as practical experience with real-world scenarios.
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