Question

I need a query that subtracts or adds according to a condition for SQLite using the CASE statement. This is my query at the moment:

SELECT s.companyName, CASE ia.type 
                      WHEN ia.type='add' THEN SUM(ia.quantity) 
                      WHEN ia.type='subtract' THEN SUM(-ia.type) 
                      ELSE SUM(0) END AS total
FROM stocktake s 
LEFT JOIN stocktake_adjustment sa ON s.stocktakeId = sa.stocktakeId
LEFT JOIN adjustment a ON a.adjustmentId = sa.adjustmentId
LEFT JOIN inventory_adjustment ia ON ia.adjustmentId = a.adjustmentId
LEFT JOIN inventory i ON i.inventoryId = ia.inventoryId 
LEFT JOIN supplier s ON s.supplierId = i.supplierId 
WHERE s.supplierId = '4da99b63-fcb9-9b9f-8415-4896caeb920c'; 

Basically I want to add if the condition is ‘add’ or subtract if condition is subtract, from the total.

Thank you in advance guys.

Answer 1

Move your CASE into SUM:

SELECT s.companyName, SUM(CASE ia.type 
                          WHEN ia.type='add' THEN ia.quantity
                          WHEN ia.type='subtract' THEN -ia.quantity 
                          ELSE 0 
                          END)
                      AS total
FROM stocktake s 
LEFT JOIN stocktake_adjustment sa ON s.stocktakeId = sa.stocktakeId
LEFT JOIN adjustment a ON a.adjustmentId = sa.adjustmentId
LEFT JOIN inventory_adjustment ia ON ia.adjustmentId = a.adjustmentId
LEFT JOIN inventory i ON i.inventoryId = ia.inventoryId 
LEFT JOIN supplier s ON s.supplierId = i.supplierId 
WHERE s.supplierId = '4da99b63-fcb9-9b9f-8415-4896caeb920c';

(I assumed that -ia.type in the original question was a typo, really meaning -ia.quantity)