我有这个联合查询:
(SELECT INSTALLER, INSTALLTIME, RESULT, JOBNUMBER, HONAME, ADDRESS, CITY, STATE, ZIP, NOTES, SMNOTES, '' as priority, PAFS, upsell, TERM, MMRUPGRADE, WARRANTY, EFT FROM ACCOUNTS
WHERE INSTALLDATE = '$date' && FUNDINGSTATUS !='DEAD')
UNION
(SELECT technician, servicetime, result, ID, Customername, address, city, state, zip, notes, board, priority, '', '', '', '', '', '' FROM service
WHERE serviceday = '$date')
ORDER BY INSTALLER, priority
我很好奇在日期字段上放置索引是否有助于加快这两个查询?还是我在第一个 where 子句中使用 FUNDINGSTATUS 的事实会使该查询不使用索引?