My Performance Observation found similar counting plans for a nonempty table. SUM(1) and COUNT(*) still differ on empty input.
Conditional Aggregation: Several Counts in One Pass With CASE
Use conditional aggregation for several ticket counts, avoid COUNT with ELSE zero, and calculate percentages with an explicit denominator.
COUNT(*) and COUNT(1): Performance Battle – SQL in Sixty Seconds #176
COUNT(*) and COUNT(1): Performance Battle – which one is better for performance? I got this question after watching my previous video.
COUNT(*) and Index Frequently Asked Questions
My Index Frequently Asked Questions discussion follows the counting video. I distinguish exact results, estimates and the expression being counted.
COUNT(*) and Index – SQL in Sixty Seconds #175
Earlier I wrote two blog post on the topic of COUNT(*) and Index and today I have to build a video on that topic as many of you really wanted.
Count Distinct in Access: Use a Subquery in FROM
Count distinct in Access with a subquery in the FROM clause, because Access SQL does not accept COUNT(DISTINCT). Includes NULL and multi-column cases.
SQL SERVER – Identity Column is Difficult to Remove
The IDENTITY property is difficult to remove through a column alteration because SQL Server doesn’t support that operation. Existing values need protection.