﻿ SQL exercises on employee Database: List the employees who are working for the department ID 1001 or 2001 - w3resource

# SQL exercises on employee Database: List the employees who are working for the department ID 1001 or 2001

## SQL employee Database: Exercise-37 with Solution

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37. From the following table, write a SQL query to find those employees who are working for the department ID 1001 or 2001.Return complete information about the employees.

Sample table: employees

Pictorial Presentation:

Sample Solution:

``````SELECT *
FROM employees
WHERE dep_id=1001
OR dep_id=2001;
``````

Sample Output:

``` emp_id | emp_name | job_name  | manager_id | hire_date  | salary  | commission | dep_id
--------+----------+-----------+------------+------------+---------+------------+--------
68319 | KAYLING  | PRESIDENT |            | 1991-11-18 | 6000.00 |            |   1001
67832 | CLARE    | MANAGER   |      68319 | 1991-06-09 | 2550.00 |            |   1001
65646 | JONAS    | MANAGER   |      68319 | 1991-04-02 | 2957.00 |            |   2001
67858 | SCARLET  | ANALYST   |      65646 | 1997-04-19 | 3100.00 |            |   2001
69062 | FRANK    | ANALYST   |      65646 | 1991-12-03 | 3100.00 |            |   2001
63679 | SANDRINE | CLERK     |      69062 | 1990-12-18 |  900.00 |            |   2001
68736 | ADNRES   | CLERK     |      67858 | 1997-05-23 | 1200.00 |            |   2001
69324 | MARKER   | CLERK     |      67832 | 1992-01-23 | 1400.00 |            |   1001
(8 rows)
```

Relational Algebra Expression:

Relational Algebra Tree:

## Practice Online

Sample Database: employee

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## SQL: Tips of the Day

MYSQL OR vs IN performance:

In many database servers, IN() is just a synonym for multiple OR clauses, because the two are logically equivalent. Not so in MySQL, which sorts the values in the IN() list and uses a fast binary search to see whether a value is in the list. This is O(Log n) in the size of the list, whereas an equivalent series of OR clauses is O(n) in the size of the list (i.e., much slower for large lists)

Ref: https://bit.ly/3PzLY69