Final answer:
In SQL, INTERSECT command finds common data between two datasets, while EXCEPT subtracts one set from another. It's important to understand subquery results to ensure accurate SQL statements. Common database user privileges include SELECT, INSERT, UPDATE, and DELETE.
Step-by-step explanation:
Combining SQL Query Results:
To combine results from two SQL queries, you can use UNION, INTERSECT, or EXCEPT commands. The INTERSECT command returns only the rows that are present in both query results, essentially finding the common data between two datasets. On the other hand, the EXCEPT command returns only the rows from the first query that are not found in the second query, essentially subtracting one set of data from another.
Subqueries:
Regarding subqueries, there are three types: scalar, where the subquery returns a single value; row, where the subquery returns a single row of values; and table, where the subquery returns multiple rows and columns. Understanding the nature of subquery results before writing an SQL statement is crucial because it determines how the subquery can be incorporated into the main query, which affects the accuracy and performance of the SQL statement.
Integrity Enhancement Feature (IFF):
The Integrity Enhancement Feature (IFF) is fictional in the context of SQL databases, but it may refer to features that enhance integrity such as constraints which ensure that data adheres to specific rules, maintaining data accuracy and reliability within the database.
Database User Privileges:
Common privileges granted to database users include SELECT, which allows reading data; INSERT, which allows adding data; UPDATE, which allows modifying existing data; and DELETE, which allows removing data. These privileges are important in controlling access to the data and maintaining database security.