﻿ SQL: Information about the department Marketing

# SQL Exercise: Information about the department Marketing

## SQL SORTING and FILTERING on HR Database: Exercise-5 with Solution

5. From the following table, write a SQL query to find the details of 'Marketing' department. Return all fields.

Sample table: departments

Sample Solution:

``````SELECT *
FROM  departments
WHERE department_name = 'Marketing';
``````

Sample Output:

``` department_id | department_name | manager_id | location_id
---------------+-----------------+------------+-------------
20 | Marketing       |        201 |        1800
(1 row)
```

Code Explanation:

The said query in SQL that retrieves all columns from the 'departments' table where the department name is 'Marketing'. As a result of the query, a list of all rows in the 'departments' table that match the conditions specified in the "WHERE" clause is returned. The "SELECT *" clause retrieves all columns from the table.

Relational Algebra Expression:

Relational Algebra Tree:

## Query Visualization:

Duration:

Rows:

Cost:

Previous SQL Exercise: Details of employees without any department number.
Next SQL Exercise: Employees first name does not contain the letter M .

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## SQL: Tips of the Day

Difference between natural join and inner join

One significant difference between INNER JOIN and NATURAL JOIN is the number of columns returned-

Consider:

```TableA                           TableB
+------------+----------+        +--------------------+
|Column1     | Column2  |        |Column1  |  Column3 |
+-----------------------+        +--------------------+
| 1          |  2       |        | 1       |   3      |
+------------+----------+        +---------+----------+
```

The INNER JOIN of TableA and TableB on Column1 will return

```SELECT * FROM TableA AS a INNER JOIN TableB AS b USING (Column1);
SELECT * FROM TableA AS a INNER JOIN TableB AS b ON a.Column1 = b.Column1;
```
```+------------+-----------+---------------------+
| a.Column1  | a.Column2 | b.Column1| b.Column3|
+------------------------+---------------------+
| 1          |  2        | 1        |   3      |
+------------+-----------+----------+----------+
```

The NATURAL JOIN of TableA and TableB on Column1 will return:

```SELECT * FROM TableA NATURAL JOIN TableB
+------------+----------+----------+
|Column1     | Column2  | Column3  |
+-----------------------+----------+
| 1          |  2       |   3      |
+------------+----------+----------+
```

Ref: https://bit.ly/3AG5CId

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