1. What is Oracle SQL?
Oracle SQL (Structured Query Language) is the language used to interact with an Oracle database. It’s used to retrieve and manipulate data in the database.
2. What is the difference between SQL and Oracle SQL?
SQL is a standard language used for managing and manipulating relational databases, while Oracle SQL is the specific implementation of the SQL language used to interact with Oracle databases.
3. How can you sort data in Oracle SQL?
Data can be sorted in Oracle SQL using the ORDER BY clause in a SELECT statement. The ORDER BY clause specifies the column or columns that should be used to sort the data and the sort order (ascending or descending).
4. What is a constraint in Oracle SQL?
A constraint in Oracle SQL is a rule that restricts the data that can be stored in a table. Constraints can be used to enforce business rules and to maintain data integrity. Some common types of constraints include NOT NULL, UNIQUE, and FOREIGN KEY constraints.
5. What is a join in Oracle SQL?
A join in Oracle SQL is a way to combine rows from two or more tables based on a related column between them. There are several types of joins, including INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL OUTER JOIN.
6. What is the difference between INNER JOIN and OUTER JOIN in Oracle SQL?
An INNER JOIN returns only the rows that have matching values in both tables, while an OUTER JOIN returns all the rows from one table and the matching rows from the other table. There are three types of outer joins: LEFT JOIN, RIGHT JOIN, and FULL OUTER JOIN.
7. What is a subquery in Oracle SQL?
A subquery in Oracle SQL is a query nested inside another query. The inner query is executed first and its result is used by the outer query. Subqueries are used to return data that will be used in the main query as a condition to further restrict the data to be retrieved.
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