sql

Question 1

What is the fundamental approach of SQL in terms of data manipulation?

Answer 1

they are not the core concept of SQL being set-oriented.

Question 2

What is the primary difference between a declarative language like SQL and a procedural language like C++?

Answer 2

Declarative: In a declarative language like SQL, you specify what you want to achieve (e.g., “Select all customers from the Customers table”). The system determines how to achieve it.

Question 3

What are the two primary ways SQL can be used?

Answer 3

interactive embedded

Question 4

What is the primary function of the SELECT statement in SQL?

Answer 4

The primary function of the SELECT statement is to retrieve data from a relational database.

Question 5

What is the primary function of the WHERE clause in a SQL SELECT statement?

Answer 5

While the WHERE clause can filter data horizontally (selecting specific rows based on conditions), its primary function is to apply conditions to the dataset.

Here’s a more accurate explanation:

Filtering: The WHERE clause filters rows based on specified conditions.
Conditions: These conditions are typically expressed using comparison operators (e.g., =, <, >, <>, BETWEEN, IN) and logical operators (e.g., AND, OR, NOT).

Question 6

What is the primary function of the GROUP BY clause in a SQL SELECT statement?

Answer 6

Grouping: The GROUP BY clause specifies the columns by which you want to group the data.
Aggregation: You often use aggregate functions (like SUM, AVG, COUNT, MIN, MAX) with GROUP BY to calculate values for each group.

Question 7

What is the difference between an inner join and an outer join in SQL?

Answer 7

Inner join:

Returns only the rows that have matching values in both tables. It’s like finding the overlap between two sets of data.
Outer join: Returns all rows from one table, even if there are no matching rows in the other table. It’s like merging two sets of data, including the parts that don’t overlap.