﻿ SQL: Display the winners in Physics for 1970 together with the winner of Economics for 1971 - w3resource

# SQL: Display the winners in Physics for 1970 together with the winner of Economics for 1971

## SQL Basic Select Statement: Exercise-19 with Solution.

From the following table, write a SQL query that combines the winners in Physics, 1970 and in Economics, 1971. Return year, subject, winner, country, and category.

Sample table: nobel_win

Sample Solution:

``````SELECT * FROM nobel_win  WHERE (subject ='Physics' AND year=1970) UNION (SELECT * FROM nobel_win  WHERE (subject ='Economics' AND year=1971));
``````

Output of the Query:

```year	subject		winner		country	  category
1970	Physics		Hannes Alfven	Sweden	 Scientist
1970	Physics		Louis Neel	France	 Scientist
1971	Economics	Simon Kuznets	Russia	 Economist```

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