Some useful MySQL queries for ready reference

Finding non-unique values in a column:

SELECT 
    col_name, 
    COUNT(col_name)
FROM
    table_name
GROUP BY col_name
HAVING COUNT(col_name) > 1;

Use of Case When:

SELECT 
	category, 
	SUM(CASE WHEN topic="stock_at_factory" AND `range`="daily" THEN qty_kg ELSE 0 END) AS stock_at_factory, 
	SUM(CASE WHEN topic="stock_at_market"  AND `range`="daily" THEN qty_kg ELSE 0 END) AS stock_at_market
FROM sku_summary 	
WHERE 
	eff_date="2024-03-11" 
	AND entity="ITL" 
  AND prod_line="TEA" 
GROUP BY category