然后是冗余行

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

看起来你想要一个带有条件聚合的GROUP BY：

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