What is NULL and how does it affect query results?

< 1 min read

NULL represents missing or unknown data in a table.
It is not the same as zero or an empty string.
NULL can affect query results in filters and calculations.
In my project, some customers had NULL phone numbers, which impacted contact reports.
Functions like COUNT(column) ignore NULLs, while COUNT(*) includes all rows.
Comparisons with NULL require IS NULL or IS NOT NULL.
Handling NULL properly ensures accurate reporting and analysis.

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