Question

所以我有一个包含2列的表

class_id | title          
CS124    | computer tactics          
CS101    | intro to computers          
MATH157  | math stuff          
CS234    | other CS stuff          
FRENCH50 | TATICS of french          
ENGR101  | engineering ETHICS      
OTHER1   | other CS title

我希望在用户搜索某些内容时进行自动完成的智能搜索。

让我们说他们输入CS＆＃39;在框中我想使用class_id和title进行搜索，限制为5，对于此示例。我首先要搜索类似于＆＃39; CS％＆＃39;的class_ids。由class_id排序的限制为5。这将返回3 cs类。

然后，如果在限制中还剩下任何空间，我想使用＆＃39;％CS％之类的标题进行搜索并合并它们，但首先要保留class_id个匹配项，并确保从中删除重复项底部就像cs234一样，在两个查询中都匹配。

因此该查询的最终结果是

CS101    | intro to computers          
CS124    | computer tactics          
CS234    | other CS stuff          
ENGR101  | engineering ETHICS          
FRENCH50 | TATICS of french

我正在尝试做这样的事情

(select * from class_infos
 where LOWER(class_id) like LOWER('CS%')
 order by class_id)

union

(select * from class_infos
 where LOWER(title) like LOWER('%CS%')
 order by class_id)

limit 30

但它并没有按照正确的顺序排列它们，或者使class id查询具有优先权。任何人都有任何建议

这是sqlfiddle http://sqlfiddle.com/#!15/5368b

Answer 1

你试过这样的事吗？

SQL Fiddle Demo

SELECT *
FROM
  (
    (select 1 as priority, * 
     from class_infos
     where LOWER(class_id) like LOWER('CS%'))
  union
    (select 2 as priority, * 
     from class_infos
     where 
             LOWER(title) like LOWER('%CS%')
     and not LOWER(class_id) like LOWER('CS%') 
    )
  ) as class
ORDER BY priority, class_id
limit 5

Postgresql联合查询优先于一个查询

1 个答案: