8. What is a view in Oracle SQL?
A view in Oracle SQL is a virtual table that is based on the result of a SELECT statement. Views can be used to simplify the data retrieval process by hiding the complexity of the underlying tables and providing a simplified version of the data to users.
9. What is the difference between an inner join and an outer join in Oracle SQL?
An inner join returns only the rows that have matching values in both tables. An outer join returns all the rows from one table and the matching rows from the other table. If there is no match, NULL values will be returned for non-matching rows from the table that is not included in the join. There are three types of outer joins: LEFT, RIGHT, and FULL.
10. How can you select unique records from a table in Oracle SQL?
You can use the DISTINCT keyword to select unique records from a table. For example: “SELECT DISTINCT column_name FROM table_name”.
11. How can you get the current date and time in Oracle SQL?
You can use the SYSDATE keyword to get the current date and time. For example: “SELECT SYSDATE FROM dual”.
12. How can you perform a pattern match in Oracle SQL?
You can use the LIKE operator to perform a pattern match. The LIKE operator allows you to search for a pattern in a string. For example: “SELECT column_name FROM table_name WHERE column_name LIKE ‘pattern'”.
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