﻿ SQL: Display all employee data for the department 57 - w3resource

# SQL: Display all employee data for the department 57

## SQL Basic Select Statement: Exercise-33 with Solution.

From the following table, write a SQL query to retrieve the details of the employees who work in the department 57. Return emp_idno, emp_fname, emp_lname and emp_dept.

Sample table: emp_details

Sample Solution:

``````SELECT *
FROM emp_details
WHERE emp_dept= 57;
``````

Output of the Query:

```emp_idno	emp_fname	emp_lname	emp_dept
839139		Maria		Foster		57
127323		Michale		Robbin		57
843795		Enric		Dosio		57
847674		Kuleswar	Sitaraman	57
555935		Alex		Manuel		57
```

Relational Algebra Expression:

Relational Algebra Tree:

## Query Visualization:

Duration:

Rows:

Cost:

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## SQL: Tips of the Day

Can a foreign key be NULL and/or duplicate?

First remember a Foreign key simply requires that the value in that field must exist first in a different table (the parent table). That is all an Foreign key is by definition. Null by definition is not a value. Null means that we do not yet know what the value is.

Ref: https://bit.ly/3uVu3OS