Which predicate correctly checks for missing values in standard SQL?

Problem Statement

Explanation

NULL represents unknown. Comparisons with equals return unknown, not true. Use IS NULL or IS NOT NULL. When aggregating, functions like COUNT(col) skip NULLs, while COUNT(*) counts all rows.

Code Solution

SolutionRead Only

SELECT COUNT(*) total, COUNT(email) with_email
FROM users
WHERE deleted_at IS NULL;

Practice Sets

This question appears in the following practice sets:

SQL Core Fundamentals

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Which predicate correctly checks for missing values in standard SQL?

Problem Statement

Explanation

Code Solution

Practice Sets

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Which predicate correctly checks for missing values in standard SQL?

Problem Statement

Explanation

Code Solution

Practice Sets

Related Questions

Which SQL statement retrieves all columns and rows from a table named employees?

Which clause filters rows before aggregation and affects which rows are grouped?

What is the default sort order when ORDER BY is used without ASC or DESC?

Which construct is commonly used to paginate results in SQL engines like Postgres and MySQL?

What is the main purpose of using column or table aliases in a SELECT statement?

More from SQL & Databases

Master Interviews
Anywhere, Anytime