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我有一个查询。在此查询中，我使用子查询从具有不同条件的同一个表中获取数据，在主查询中，我提到了用于在子查询中获取数据的 id，并设置了一个条件，即正在存在的值在主查询中考虑的 id 不应为空。如果我在主查询中使用带有 IN 子句的单个 ID，我的查询工作正常，但如果我在主查询中使用多个 id 并添加值不应为空的子句，则查询不会给我想要的结果。这是我的查询

SELECT e.id AS `Personal Number`,
e.date AS `Date`,
CONCAT(ep.firstname,' ',ep.lastname) AS `Employee Name`,
IF(ep.sex='M','Male','Female') AS sex,
DATE_FORMAT(p.birthdate,'%m/%d/%Y')AS birthdate,
(SELECT `value` FROM employee_data WHERE history=87 AND DATE=e.date) AS `A`,
(SELECT `value` FROM employee_data WHERE history=603 AND DATE=e.date) AS `B`,
(SELECT `value` FROM employee_data WHERE history=82 AND DATE=e.date) AS `C`,
(SELECT `value` FROM employee_data WHERE history=86 AND DATE=e.date) AS `D`
FROM tbl e  
INNER JOIN employee ep ON e.id = ep.id
INNER JOIN tbl2 ap ON ap.date=e.date
INNER JOIN employee_data AS phd ON e.date = phd.date   
WHERE (phd.history IN(82,87,603,86) AND phd.value!='')  AND ap.date BETWEEN '2013-01-01' AND '2013-09-01'AND e.status!='cancelled'.

我不知道如何处理这个查询。任何人都可以帮忙。提前致谢

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2 回答 2

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由于您在 select 子句中使用过滤器获取值，因此请在 select 子句中进行分组并获取 max() 值。

max (SELECT `value` FROM employee_data WHERE history=87 AND DATE=e.date) AS `A`,
max (SELECT `value` FROM employee_data WHERE history=603 AND encounter_nr=e.encounter_nr)     AS `B`,
max (SELECT `value` FROM employee_data WHERE history=82 AND encounter_nr=e.encounter_nr) AS `C`,
max  (SELECT `value` FROM employee_data WHERE history=86 AND encounter_nr=e.encounter_nr) AS `D`
FROM
于 2013-08-27T12:38:51.460 回答
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这是你的问题。where当您有该子句时，您的查询将产生四行。但是，我怀疑您只是期望一个行，或者至少每个 ID 只有一行。

我认为这是您想要的查询：

SELECT e.id AS `Personal Number`, e.date AS `Date`,
       CONCAT(ep.firstname,' ',ep.lastname) AS `Employee Name`,
       IF(ep.sex='M','Male','Female') AS sex,
       DATE_FORMAT(p.birthdate,'%m/%d/%Y') AS birthdate,
       max(case when history = 87 then value end) as A,
       max(case when history = 603 then value end) as B,
       max(case when history = 82 then value end) as C,
       max(case when history = 86 then value end) as D
FROM tbl e INNER JOIN
     employee ep
     ON e.id = ep.id INNER JOIN
     tbl2 ap ON ap.date = e.date INNER JOIN
     employee_data phd
     ON e.date = phd.date   
WHERE phd.history IN (82, 87, 603, 86) AND phd.value <> '' AND
      ap.date BETWEEN '2013-01-01' AND '2013-09-01' AND
      e.status <> 'cancelled'
group by e.id;

这应该为每个员工返回一行。

编辑：

我突然想到您可能不想要聚合。employee_data您可以通过删除外部查询中的联接来遵循您的原始方法：

SELECT e.id AS `Personal Number`, e.date AS `Date`,
       CONCAT(ep.firstname,' ',ep.lastname) AS `Employee Name`,
       IF(ep.sex='M','Male','Female') AS sex,
       DATE_FORMAT(p.birthdate,'%m/%d/%Y') AS birthdate,
       (SELECT `value` FROM employee_data WHERE history=87 AND DATE=e.date) AS `A`,
       (SELECT `value` FROM employee_data WHERE history=603 AND DATE=e.date) AS `B`,
       (SELECT `value` FROM employee_data WHERE history=82 AND DATE=e.date) AS `C`,
       (SELECT `value` FROM employee_data WHERE history=86 AND DATE=e.date) AS `D`
FROM tbl e INNER JOIN
     employee ep
     ON e.id = ep.id INNER JOIN
     tbl2 ap ON ap.date = e.date
WHERE ap.date BETWEEN '2013-01-01' AND '2013-09-01'AND e.status <> 'cancelled'
HAVING A <> '' and B <> '' and C <> '' and D <> '';

该having子句是一种 MySQL 技巧，可让您在from子句中引用列别名。在这种情况下，它并不意味着聚合。

如果你有一个 index ，你会这样做employee_data(history, date)。

于 2013-08-27T12:44:26.007 回答