SQL

group by por mes sql mysql

SELECT COUNT(idcompra) 
FROM compra 
WHERE YEAR(fecha_compra) = 2021 GROUP BY MONTH(fecha_compra)

MySQL GROUP BY

SELECT 
    c1, c2,..., cn, aggregate_function(ci)
FROM
    table
WHERE
    where_conditions
GROUP BY c1 , c2,...,cn;

MySQL GROUP BY

SELECT Manufacturer, COUNT(*) AS ModelsCount
FROM Products
WHERE Price > 30000
GROUP BY Manufacturer
ORDER BY ModelsCount DESC