Question

如何使用union和join优化查询？是否有可能在联盟之外移动一些连接？

(
    SELECT accounting.id, accounting.time, accounting.subaccount_id AS module_id, accounting.balance_invoice_id AS balance_id, accounting.currency_amount*-1 AS currency_amount, accounting.amount*-1 AS amount, enclosure.enc_id_, enclosure.txt, currency.name AS currency_name, IF(balance_invoice.amount, accounting.currency_amount*-1+SUM(balance_invoice.amount), accounting.currency_amount*-1) AS balance
    FROM accounting
    INNER JOIN enclosure ON enclosure.id=accounting.enc_id
    LEFT JOIN currency ON currency.id=accounting.currency_id
    LEFT JOIN balance_invoice ON balance_invoice.accounting_id=accounting.id
    WHERE accounting.att_booked=1
    GROUP BY accounting.id
)
UNION (
    SELECT accounting.id, accounting.time, accounting.subaccountoff_id AS module_id, accounting.balanceoff_invoice_id AS balance_id, accounting.currency_amount, accounting.amount, enclosure.enc_id_, enclosure.txt, currency.name AS currency_name, IF(balance_invoice.amountoff, accounting.currency_amount+SUM(balance_invoice.amountoff), accounting.currency_amount) AS balance
    FROM accounting
    INNER JOIN enclosure ON enclosure.id=accounting.enc_id
    LEFT JOIN currency ON currency.id=accounting.currency_id
    LEFT JOIN balance_invoice ON balance_invoice.accounting_id=accounting.id
    WHERE accounting.att_booked=1 && accounting.type IN (0,1,2)
    GROUP BY accounting.id
) ORDER BY time DESC

Answer 1

这也应该在没有UNION的情况下工作。我使用了几个CASE语句。未测试的：

SELECT a.id, a.time
      ,CASE WHEN a.type IN (0,1,2) THEN a.subaccountoff_id      ELSE a.subaccount_id      END AS module_id
      ,CASE WHEN a.type IN (0,1,2) THEN a.balanceoff_invoice_id ELSE a.balance_invoice_id END AS balance_id
      ,CASE WHEN a.type IN (0,1,2) THEN a.currency_amount       ELSE a.currency_amount*-1 END AS currency_amount
      ,CASE WHEN a.type IN (0,1,2) THEN a.currency_amount       ELSE a.amount*-1          END AS amount
      ,e.enc_id_, e.txt, c.name AS currency_name
      ,CASE WHEN a.type IN (0,1,2)
            THEN IF (b.amountoff, a.currency_amount + SUM(b.amountoff), a.currency_amount) 
            ELSE IF (b.amount,    a.currency_amount*-1 + SUM(b.amount), a.currency_amount*-1) END AS balance
FROM   accounting a
JOIN   enclosure e ON e.id = a.enc_id
LEFT   JOIN currency c ON c.id = a.currency_id
LEFT   JOIN balance_invoice b ON b.accounting_id = a.id
WHERE  a.att_booked = 1
GROUP  BY a.id
ORDER  BY a.time DESC

优化联合查询中的联接

1 个答案: