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Course Content

Introduction to SQL

Checking for NO ValueChecking for NO Value

When a column doesn't have any value, it's regarded as having a NULL value. To identify whether a value is NULL, we check if it's equal to NULL. Alternatively, the SELECT statement provides a WHERE clause and an IS NULL clause, which is used to examine columns with NULL values. Let's illustrate this with an example:

Task

Write an SQL query that returns the name and capital columns with no population.

Here's a short example of the country table:

idnamecontinentregionsurfaceareacapitalpopulation
1JapanAsiaEastern Asia377829Tokyo126714000
2LatviaEuropeNULL64589Riga2424200
3MexicoNorth AmericaCentral America1958201Mexico City98881000
.....................
15MaltaEuropeSouthern Europe316Valletta380200

Everything was clear?

Section 3. Chapter 6
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