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SQL, PostgreSQL and data processing
Practical guides to SQL, PostgreSQL and data processing: NULL comparisons, encodings, query behavior, sources and limitations.
Working with data involves comparison rules, encodings and tool behavior as well as results. These guides explain common causes of errors and ways to investigate them.
Practical guides
2 guidesWhy SQL comparisons with NULL do not behave like zero
Understand IS NULL, three-valued logic and the difference between COUNT(*) and COUNT(column).
SQL / PostgreSQL / NULL