The number one question when showing multiple ways to return the same result set in SQL Server is, "which one performs better?" For this post I'm going to compare COUNT vs. SUM on 1 million rows, ...
SQL COUNT() is the #1 screening question for data roles. ⚠️ Get it wrong = automatic rejection. Your next interview depends on these. Including NULLs COUNT(*) / COUNT(1) → counts all rows 🚫 Excluding ...
COUNT_BIG(*) returns the number of items in a group. This includes NULL values and duplicates. COUNT_BIG (ALL expression) evaluates expression for each row in a group, and returns the number of ...
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