冗餘行隨後在回答

Question

SELECT item_id, 
     CREDITBAL= (SELECT Sum(quantity) 
        FROM axi_quantity_registers 
        WHERE from_where != 'OPENING' 
          AND transaction_type = 'C'), 
     OPENBAL = (SELECT Sum(quantity) 
        FROM axi_quantity_registers 
        WHERE from_where = 'OPENING'), 
     DEBITBAL = (SELECT Sum(quantity) 
        FROM axi_quantity_registers 
        WHERE transaction_type = 'D') 
FROM axi_quantity_registers 

Answer 1

看起來像你想有一個GROUP BY有條件聚集：

SELECT item_id, 
     sum(case when from_where != 'OPENING' AND transaction_type = 'C' then quantity end) as CREDITBAL, 
     sum(case when from_where = 'OPENING' then quantity end) as OPENBAL, 
     sum(case when transaction_type = 'D' then quantity end) as DEBITBAL 
FROM axi_quantity_registers 
group by item_id