Counting Distinct Records in SQL Databases Using GROUP BY, HAVING, and DISTINCT

Using n_distinct to Extract Unique Values by Specific Conditions in R Data Analysis

Optimizing MySQL COUNT Function Queries with Effective Index Usage

Counting the Number of Specific Integers per Column in an R Matrix

Counting Orders by Route: A Step-by-Step SQL Solution

Displaying Group By Results in Columns with SQL PIVOT Operator

How to Aggregate Events by Year in SQL Server with Conditional SUM Statements

Mapping Distinct Values to Counts in a Chart with ggplot2: A Comparative Analysis of geom_bar() and geom_col()

How to Fix ArrayOutOfBounds Exception in H2 Database with Large Grouped Queries