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What is the difference between SELECT, COUNT(*), and COUNT(1)?

SQLeasy0.5 min readPremium
Frequency
Low
Asked at 1 company
Category
487
questions in SQL
Difficulty Split
130E|271M|86H
in this category
Total Bank
1,863
across 7 categories
Asked at these companies
EY
Expert AnswerPremium
95 wordsInterview-ready
SELECT * returns all columns. COUNT(*) counts all rows including NULLs. COUNT(1) counts rows using literal 1 (same as COUNT(*)). COUNT(column) counts non-NULL values in that column. In practice, COUNT(*) and COUNT(1) are equivalent—optimizers treat them alike. Use COUNT(*) for total rows; COUNT(column) when excluding NULLs matters. Best practice: Prefer COUNT(*) for clarity; avoid COUNT(*) when you need non-NULL count of a specific column....
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