Question

正如标题所说。我有一个约需2分钟的SQL问题。 SQL问题如下所示：

SELECT *,
(SELECT (CASE WHEN `Grupp_ID` > 0 THEN `Grupp_Name` ELSE  `Customers`.`Customer` END) AS `Cust` FROM `Customers` WHERE `Customers`.`ID` = `ordrar`.`CustomerNr`) AS `GruppName`,
(SELECT SUM(REPLACE(`Hours`,',','.')) FROM `anarbetstid` WHERE `order` = `ordrar`.`order`) AS `Hours`,
(SELECT SUM(REPLACE(`Amount`,',','.')) FROM `Resa` WHERE `order` = `ordrar`.`order`) AS `Resor`,
(SELECT COUNT(*) FROM `anmaterial` WHERE `Order` = `ordrar`.`order`) AS `Material`,
(SELECT SUM(REPLACE(`Hours`,',','.') * (SELECT REPLACE(`TimePrice`,',','.') FROM `Arbetstid` WHERE `TimeCode` = `anarbetstid`.`TimeCode`)) FROM `anarbetstid` WHERE `order` = `ordrar`.`order`) AS `TimmarSum`,
(SELECT SUM(REPLACE(`Antal`,',','.') * (SELECT REPLACE(`Price`,',','.') FROM `reselist` WHERE `ID` = `Resa`.`Restyp`)) FROM `Resa` WHERE `order` = `ordrar`.`order`) AS `ResorSum`,
(SELECT CASE `palagg` WHEN 0 THEN SUM((REPLACE(`Rabatt`,',','.') * REPLACE(`Price`,',','.')) * REPLACE(`Amount`,',','.'))
WHEN 1 THEN SUM((REPLACE(`Rabatt`,',','.') * REPLACE(`InPrice`,',','.')) * REPLACE(`Amount`,',','.'))
ELSE 0
END

FROM `anmaterial` 
WHERE `Order` = `ordrar`.`order`) AS `MaterialSum` 
FROM `ordrar` 
WHERE `ordertyp` = '3' group by `ordrar`.`order` ORDER BY `ordrar`.`ID` ASC

如果我删除＆＃34;按ordrar分组。order＆＃34;我可以让它在大约1分钟内运行。

每张桌子大约有4000行。

有人可以帮助我发现为什么执行此查询需要这么长时间的问题吗？

Answer 1

为什么不使用LEFT JOIN？我认为这个问题

SELECT *, 
(CASE WHEN `Grupp_ID` > 0 THEN `Grupp_Name` ELSE  `Customers`.`Customer` END) AS `Cust` 
...
LEFT JOIN `Customers` ON `Customers`.`ID` = `ordrar`.`CustomerNr`
...
FROM `ordrar` 
WHERE `ordertyp` = '3' group by `ordrar`.`order` ORDER BY `ordrar`.`ID` ASC

Answer 2

我忘记索引2个表了。这大大减缓了一切。

再次感谢Karthick Kumar！

SQL需要2分钟才能执行查询

2 个答案: