Question

我想显示SELECT中定义的必需列，一旦执行了一个条件并打印条件的结果，我希望SELECT中的新指定列从另一个where子句显示，依此类推，首先以某种方式，我需要解决这两个问题，之后计划是与大约10个queires混合。谢谢P.s中的一个问题，结果的所有内容都显示在列i_di1.naziv

中

SELECT bolnickiracun.id,
         bolnickiracun.id_dijagnoza1, i_di1.naziv naziv_dijagnoza1
FROM     bolnickiracun
LEFT JOIN i_dijagnoze_marko i_di1 ON bolnickiracun.id_dijagnoza1=i_di1.id
WHERE  bolnickiracun.id_dijagnoza1!="" and i_di1.naziv is null
UNION ALL
SELECT bolnickiracun.id,
         bolnickiracun.id_dijagnoza2, i_di2.naziv naziv_dijagnoza2
FROM     bolnickiracun
LEFT JOIN i_dijagnoze_marko i_di2 ON bolnickiracun.id_dijagnoza2=i_di2.id
WHERE  bolnickiracun.id_dijagnoza2!="" and i_di2.naziv is null

我希望结果看起来像这样：

id id_dijagnoza1   naziv_dijagnoza1   id_dijagnoza2   naziv_dijagnoza2
1     some data         null             
2     some data         null
3                                        some data         null
4                                        some data         null

指向找到naziv_dijagnoza1或naziv_dijagnoza2，其中为null，即，外键显示不存在主键，或者某人导入不存在作为主键的错误外键。

Answer 1

这个3 SELECT的示例（第三个通过基于可以看到的模式进行推导预测）应该有助于理解您对10 SELECT的整个查询需要做什么。您需要在每个NULL中不需要的SELECT子句后的每一列填充SELECT。

SELECT bolnickiracun.id, bolnickiracun.id_dijagnoza1, i_di1.naziv naziv_dijagnoza1, NULL, NULL, NULL, NULL -- and so on
FROM     bolnickiracun
LEFT JOIN i_dijagnoze_marko i_di1 ON bolnickiracun.id_dijagnoza1=i_di1.id
WHERE  bolnickiracun.id_dijagnoza1!="" and i_di1.naziv is null

UNION ALL

SELECT bolnickiracun.id, NULL, NULL, bolnickiracun.id_dijagnoza2, i_di2.naziv naziv_dijagnoza2, NULL, NULL -- and so on
FROM     bolnickiracun
LEFT JOIN i_dijagnoze_marko i_di2 ON bolnickiracun.id_dijagnoza2=i_di2.id
WHERE  bolnickiracun.id_dijagnoza2!="" and i_di2.naziv is null

UNION ALL

SELECT bolnickiracun.id, NULL, NULL, NULL, NULL, bolnickiracun.id_dijagnoza3, i_di3.naziv naziv_dijagnoza3 -- and so on
FROM     bolnickiracun
LEFT JOIN i_dijagnoze_marko i_di3 ON bolnickiracun.id_dijagnoza3=i_di3.id
WHERE  bolnickiracun.id_dijagnoza3!="" and i_di3.naziv is null

每个SELECT中的列数应该相同，正如您所看到的，对于3 SELECT s，它是7列（每个表2个连接x 3 SELECT s + 1带ID的第一列）。对于10 SELECT s，每个SELECT子句中将有21列（1代表id，2代表每个表，其余代表NULL s）。不是很好的解决方案，但可能只有数据库结构。

因此对于10 SELECT来说，首先应该是这样的：

    SELECT bolnickiracun.id, bolnickiracun.id_dijagnoza1, i_di1.naziv naziv_dijagnoza1, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
FROM     bolnickiracun
LEFT JOIN i_dijagnoze_marko i_di1 ON bolnickiracun.id_dijagnoza1=i_di1.id
WHERE  bolnickiracun.id_dijagnoza1!="" and i_di1.naziv is null

UNION ALL
...
UNION ALL

SELECT bolnickiracun.id, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, bolnickiracun.id_dijagnoza10, i_di10.naziv naziv_dijagnoza10
FROM     bolnickiracun
LEFT JOIN i_dijagnoze_marko i_di10 ON bolnickiracun.id_dijagnoza10=i_di10.id
WHERE  bolnickiracun.id_dijagnoza10!="" and i_di10.naziv is null

如何连接多个SQL查询的结果

1 个答案: