PHP,MySQL - 从单个JOIN返回多个可识别的行？

Question

我有三张桌子,比如:

*table1*

id | val1 | val2 | val3 | val4 | val5
 1 |  ... |  ... |  ... |  ... |  ...
 2 |  ... |  ... |  ... |  ... |  ...
 3 |  ... |  ... |  ... |  ... |  ...
... etc

和

*table2*

id | som1 | som2 
 1 |  ... |  ... 
 2 |  ... |  ... 
 3 |  ... |  ... 
... etc

和

*table3*

id | col1 | col2 
 1 |  ... |  ... 
 2 |  ... |  ... 
 3 |  ... |  ... 
... etc

其中col2在第三表将总是包含从一个单一的值val3,val4或val5从第一个表.第二个表仅包含在完整性问题中,而不是问题.

我的查询如下:

$db = new PDO(...);
$stmt = $db->prepare("SELECT t2.som1 AS t2som1,
                             t1.val1 AS t1v1,
                             t1.val2 AS t1v2,
                             t1.val3 AS t1v3,
                             t1.val4 AS t1v4,
                             t1.val5 AS t1v5,
                             t3.col1 AS t3col1
                        FROM table1 t1
                          JOIN table2 t2 ON t1.val2 = t2.som2
                          JOIN table3 t3 ON t1.val3 = t3.col2
                        WHERE (t1.val4=:input OR t1.val5=:input) 
                        AND (t1.val1=1 OR t1.val1=2)");

$stmt->execute(array('input'=>$inputVal));
$result = $stmt->fetchAll();

这完全符合预期.

但!

我不只是需要t3col1进行t1.val3 = t3.col2.我还需要它t1.val4 = t3.col2和t1.val5 = t3.col2

我可以构建这条线:

JOIN table3 t3 ON (t1.val3 = t3.col2 OR t1.val4 = t3.col2 OR t1.val5 = t3.col2)

但我不知道哪个值被用来获取t3col1.它只返回一个值,而不是全部三个.

看我的问题!？

我想要

SELECT t2.som1 AS t2som1,
        ...
        t3.col1 AS t3col1, // for condition t1.val3 = t3.col2
        t3.col1 AS t3col2, // for condition t1.val4 = t3.col2
        t3.col1 AS t3col3  // for condition t1.val5 = t3.col2

可以这样做吗？

澄清

IF val1,val2并且val3都包含价值观,我想一个单一的返回行,从表3的所有三场比赛.不是三个单独的行,除了匹配列之外都是相同的.

这个SQLFiddle是我不想要的一个例子.请注意,除了t3col1列之外,一切都是相同的.这应该是一行,包含所有t3col1值.

/澄清

我估计我可以分三次加入桌子:

SELECT t2.som1 AS t2som1,
        ...
        t3.col1 AS t3col1
        t4.col1 AS t3col2
        t5.col1 AS t3col3
FROM table1 t1
  JOIN table2 t2 ON t1.val2 = t2.som2
  JOIN table3 t3 ON t1.val3 = t3.col2 // for condition t1.val3 = t3.col2
  JOIN table3 t4 ON t1.val4 = t3.col2 // for condition t1.val4 = t3.col2
  JOIN table3 t5 ON t1.val5 = t3.col2 // for condition t1.val5 = t3.col2
WHERE (...) 
AND (...)

但是这样做会失去性能(即4个JOINS),与我试图这样做的方式相反,只有2个？

奖金!

有时 val3,val4和/或val5将是空的(但永远不会col2是空的).对于那些空值的情况,所有table3 JOIN都需要是s吗？LEFT JOIN

编辑1

根据您的要求,我已经在SQLFiddle中进行了设置,但是这项服务非常突破.

你可以在这里找到它

编辑2

我尝试多次加入table3:

SELECT t2.som1 AS t2som1,
        ...
        t3.col1 AS t3col1
        t4.col1 AS t3col2
        t5.col1 AS t3col3
FROM table1 t1
  JOIN table2 t2 ON t1.val2 = t2.som2
  JOIN table3 t3 ON t1.val3 = t3.col2 // for condition t1.val3 = t3.col2
  JOIN table3 t4 ON t1.val4 = t3.col2 // for condition t1.val4 = t3.col2
  JOIN table3 t5 ON t1.val5 = t3.col2 // for condition t1.val5 = t3.col2
WHERE (...) 
AND (...)

并最终获得每场比赛的一排.我应该有7个结果,最终获得超过90个.

val1将始终具有值,并且每次是否val2和val3填充都是不同的.但是当这三个都有价值时,我不想要三个单独的回报.相反,我只想要一个包含所有三个匹配的回归.

编辑4(澄清是3 ...)

由于Siraj的回答,EDIT 2 的多个JOIN最终正在工作.问题是我用过:

JOIN table3 t3 ON t1.val3 = t3.col2 
JOIN table3 t4 ON t1.val4 = t3.col2 
JOIN table3 t5 ON t1.val5 = t3.col2

当我应该使用时:

JOIN table3 t3 ON t1.val3 = t3.col2 
JOIN table3 t4 ON t1.val4 = t4.col2 
JOIN table3 t5 ON t1.val5 = t5.col2

请注意区别？它只是t3.col2在每个等号之后 - 他们需要引用正确的表格!其余的都保持不变,鲍勃是你的阿姨!

Answer 1

下面的查询将为您提供您想要的数据：

SELECT t2.som1 AS t2som1,
 t1.val1 AS t1v1,
 t1.val2 AS t1v2,
 t1.val3 AS t1v3,
 t1.val4 AS t1v4,
 t1.val5 AS t1v5,
 t3.col1 AS t3col1,
 t3.col2 AS t3col2,
 CASE WHEN t1.val3 = t3.col2 THEN t3.col1 ELSE '' END AS 't3col11',
 CASE WHEN t1.val4 = t3.col2 THEN t3.col1 ELSE '' END AS 't3col21',
 CASE WHEN t1.val5 = t3.col2 THEN t3.col1 ELSE '' END AS 't3col31',
 CASE WHEN t1.val3 = t3.col2 THEN 't1col3'
 ELSE CASE WHEN t1.val4 = t3.col2 THEN 't1col4' ELSE 't1col5'
 END END AS ColumnName
FROM table1 t1
  JOIN table2 t2 ON t1.val2 = t2.som2
  JOIN table3 t3 ON (t1.val3 = t3.col2 OR t1.val4 = t3.col2 OR t1.val5 = t3.col2)
GROUP BY t2som1,t1v1, t1v2, t1v3, t1v4, t1v5

最后一列“ColumnName”告诉您 t1 列是与该值匹配的列。

编辑 - 使用左连接

SELECT t2.som1 AS t2som1,
t1.val1 AS t1v1,
t1.val2 AS t1v2,
t1.val3 AS t1v3,
t1.val4 AS t1v4,
t1.val5 AS t1v5,
t3.col1 AS t3col1,
    t3.col1 AS t3col1,
    t4.col1 AS t3col2,
    t5.col1 AS t3col3
FROM table1 AS t1
LEFT JOIN table2 t2 ON t1.val2 = t2.som2
LEFT JOIN table3 t3 ON t1.val3 = t3.col2
LEFT JOIN table3 t4 ON t1.val4 = t4.col2
LEFT JOIN table3 t5 ON t1.val5 = t5.col2