Mysql查询代码改进

我对编码相当陌生，并且通过我自己的兴趣，我尝试为工作创建一个数据库系统，并且随着我的进展非常多地学习。Mysql查询代码改进

我有一个数据库查询，它旨在显示Sample Name,Tank Name和Customer匹配的最近结果。这些来自三个不同但相关的表格。

我想出了以下查询。 这个查询工作，但为了我自己的教育，我沿着正确的路线工作，还是有更好的方法来解决这个问题（这看起来很不整洁，很难在我的脑海里读到）？

SELECT 
    `t_workorders`.`Work Order`, 
    `t_workorders`.`Date Sampled`, 
    `Result`, 
    `t_test_units`.`Unit` 
FROM 
    `t_sampletests` 
    RIGHT JOIN `t_samples` 
    ON `Sample` = `pk_Sample` 
    RIGHT JOIN `t_workorders` 
    ON `t_samples`.`Work Order` = `t_workorders`.`Work Order` 
    LEFT JOIN `t_test_units` 
    ON `t_sampletests`.`Unit` = `t_test_units`.`pk_Unit` 
WHERE `t_sampletests`.`Test` = 
    (SELECT 
    `Test` 
    FROM 
    `t_sampletests` 
    WHERE `pk_SampleTest` = $ testID) 
    AND `t_Samples`.`Sample Name` = 
    (SELECT 
    `Sample Name` 
    FROM 
    `t_sampletests` 
    LEFT JOIN `t_Samples` 
     ON `Sample` = `pk_Sample` 
    WHERE `pk_SampleTest` = $ testID) 
    AND `t_Samples`.`Tank` = 
    (SELECT 
    `Tank` 
    FROM 
    `t_sampletests` 
    LEFT JOIN `t_Samples` 
     ON `Sample` = `pk_Sample` 
    WHERE `pk_SampleTest` = $ testID) 
    AND `t_workorders`.`Customer` = 
    (SELECT 
    `Customer` 
    FROM 
    `t_sampletests` 
    LEFT JOIN `t_Samples` 
     ON `Sample` = `pk_Sample` 
    LEFT JOIN `t_workorders` 
     ON `t_Samples`.`Work Order` = `t_workorders`.`Work Order` 
    WHERE `pk_SampleTest` = $ testID) 
    AND `t_workorders`.`Work Order` <> 
    (SELECT 
    `t_workorders`.`Work Order` 
    FROM 
    `t_sampletests` 
    LEFT JOIN `t_Samples` 
     ON `Sample` = `pk_Sample` 
    LEFT JOIN `t_workorders` 
     ON `t_Samples`.`Work Order` = `t_workorders`.`Work Order` 
    WHERE `pk_SampleTest` = $ testID) 
ORDER BY `t_workorders`.`Work Order` DESC 
LIMIT 15

任何建议的替代或更合适的方法将不胜感激。

非常感谢

来源

2016-07-29 Neil Sverdloff

任何问题，这个查询？ –

如何格式化它以便可以轻松读取它。使用新的线和增量..？ – John

我建议不要使用像这样的权利加入 't_workorders ..这将包括来自t_workorders的所有字段 –

国际海事组织，使用新的行和增量将帮助您阅读和结构查询，并让您有一个快速概述它能做什么。

我也尝试使用SQL关键字时一致，并将它们写入大写。

SELECT `t_workorders`.`Work Order`, `t_workorders`.`Date Sampled`, `Result`,`t_test_units`.`Unit` 
FROM `t_sampletests` 
RIGHT JOIN `t_samples` ON `Sample` = `pk_Sample` 
RIGHT JOIN `t_workorders` ON `t_samples`.`Work Order` = `t_workorders`.`Work Order` 
LEFT JOIN `t_test_units`ON `t_sampletests`.`Unit` = `t_test_units`.`pk_Unit` 
WHERE `t_sampletests`.`Test` = (
    SELECT `Test` FROM `t_sampletests` WHERE `pk_SampleTest` = $testID 
) 
    AND `t_Samples`.`Sample Name` = (
    SELECT `Sample Name` 
    FROM `t_sampletests` 
    LEFT JOIN `t_Samples` ON `Sample` = `pk_Sample` WHERE `pk_SampleTest` = $testID 
) 
    AND `t_Samples`.`Tank` = (
    SELECT `Tank` 
    FROM `t_sampletests` 
    LEFT JOIN `t_Samples` ON `Sample` = `pk_Sample` WHERE `pk_SampleTest` = $testID 
) 
    AND `t_workorders`.`Customer`= (
    SELECT `Customer` 
    FROM `t_sampletests` 
    LEFT JOIN `t_Samples` ON `Sample` = `pk_Sample` 
    LEFT JOIN `t_workorders` ON `t_Samples`.`Work Order` = `t_workorders`.`Work Order` 
    WHERE `pk_SampleTest` = $testID 
) 
    AND `t_workorders`.`Work Order` <> (
    SELECT `t_workorders`.`Work Order` 
    FROM `t_sampletests` 
    LEFT JOIN `t_Samples` ON `Sample` = `pk_Sample` 
    LEFT JOIN `t_workorders` ON `t_Samples`.`Work Order` = `t_workorders`.`Work Order` 
    WHERE `pk_SampleTest` = $testID 
) 
ORDER BY `t_workorders`.`Work Order` 
DESC LIMIT 15;

（不要忘了在;然后结束你的查询）

来源

2016-07-29 08:45:20 John

事情是这样的：

select feild1, field2 from 
(select feild1, field2 from table1)as a 

left join 

select field1, desc from table2) as b 
on a.field1 = b.field1

这将优化您的查询

避免选择你不使用它在一个表中的所有领域。选择你只想领域以显示优化

来源

2016-07-29 08:40:27

Mysql查询代码改进

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