[英]MySQL - selecting data where count is more than 1
我有下表:
+-------------------------------------+----------------------------------------------------------------+
| keyword | landing_page |
+-------------------------------------+----------------------------------------------------------------+
| orange | https://www.example.co.uk/ |
| apple | https://www.example.co.uk/ |
| pear | https://www.example.co.uk/ |
| apple | https://www.example.co.uk/ |
| apple | https://www.example.co.uk/landing-page |
+-------------------------------------+----------------------------------------------------------------+
我想選擇具有多個不同着陸頁的任何關鍵字,因此在此示例中,我們將返回:
apple, https://www.example.co.uk
apple, https://www.example.co.uk/landing-page
我怎樣才能用MySQL實現這個目標?
更新 :我嘗試了以下但它似乎不起作用:
select keyword, count(landing_page)
from search_data
group by keyword
having count(distinct landing_page) > 1;
您嘗試的查詢是解決方案的一部分。 將該查詢用作內聯視圖,以標識具有多個目標網頁的關鍵字。 將該查詢的結果連接回原始表。
SELECT t.keyword
, t.landing_page
FROM ( -- keyword with more than one landing page
SELECT r.keyword
FROM search_data r
GROUP BY r.keyword
HAVING COUNT(DISTINCT r.landing_page) > 1
) s
JOIN search_data t
ON t.keyword = s.keyword
GROUP BY t.keyword, t.landing_page
ORDER BY t.keyword, t.landing_page
這不是唯一的方法。 還有其他查詢模式也將返回等效結果。 作為另一種方法的示例,使用相關子查詢來檢查表中具有相同關鍵字但具有不同landing_page的另一行的存在:
SELECT DISTINCT t.keyword, t.landing_page
FROM search_data t
WHERE EXISTS ( SELECT 1
FROM search_data r
WHERE r.keyword = t.keyword
AND NOT ( r.landing_page <=> t.landing_page )
)
ORDER BY t.keyword, t.landing_page
跟進
演示設置:
CREATE TABLE search_data (keyword VARCHAR(10), landing_page VARCHAR(80))
;
CREATE INDEX search_data_IX1 ON search_data (keyword, landing_page)
;
INSERT INTO search_data (keyword, landing_page) VALUES
('orange','https://www.example.co.uk/')
,('apple','https://www.example.co.uk/')
,('pear','https://www.example.co.uk/')
,('apple','https://www.example.co.uk/')
,('apple','https://www.example.co.uk/landing-page')
;
EXPLAIN查詢1
EXPLAIN
SELECT t.keyword
, t.landing_page
FROM ( -- keyword with more than one landing page
SELECT r.keyword
FROM search_data r
GROUP BY r.keyword
HAVING COUNT(DISTINCT r.landing_page) > 1
) s
JOIN search_data t
ON t.keyword = s.keyword
GROUP BY t.keyword, t.landing_page
ORDER BY t.keyword, t.landing_page
-- id select_type table type possible_keys key key_len ref rows Extra
-- ------ ----------- ---------- ------ --------------- --------------- ------- ------ ------ ------------------------
-- 1 PRIMARY <derived2> system (NULL) (NULL) (NULL) (NULL) 1
-- 1 PRIMARY t ref search_data_IX1 search_data_IX1 13 const 2 Using where; Using index
-- 2 DERIVED r index (NULL) search_data_IX1 96 (NULL) 5 Using index
執行查詢1
SELECT t.keyword
, t.landing_page
FROM ( -- keyword with more than one landing page
SELECT r.keyword
FROM search_data r
GROUP BY r.keyword
HAVING COUNT(DISTINCT r.landing_page) > 1
) s
JOIN search_data t
ON t.keyword = s.keyword
GROUP BY t.keyword, t.landing_page
ORDER BY t.keyword, t.landing_page
-- keyword landing_page
-- ------- --------------------------------------
-- apple https://www.example.co.uk/
-- apple https://www.example.co.uk/landing-page
解釋查詢2
EXPLAIN
SELECT DISTINCT t.keyword, t.landing_page
FROM search_data t
WHERE EXISTS ( SELECT 1
FROM search_data r
WHERE r.keyword = t.keyword
AND NOT ( r.landing_page <=> t.landing_page )
)
ORDER BY t.keyword, t.landing_page
-- id select_type table type possible_keys key key_len ref rows Extra
-- ------ ------------------ ------ ------ --------------- --------------- ------- -------------- ------ -------------------------------------
-- 1 PRIMARY t range (NULL) search_data_IX1 96 (NULL) 6 Using where; Using index for group-by
-- 2 DEPENDENT SUBQUERY r ref search_data_IX1 search_data_IX1 13 test.t.keyword 1 Using where; Using index
執行查詢2
SELECT DISTINCT t.keyword, t.landing_page
FROM search_data t
WHERE EXISTS ( SELECT 1
FROM search_data r
WHERE r.keyword = t.keyword
AND NOT ( r.landing_page <=> t.landing_page )
)
ORDER BY t.keyword, t.landing_page
-- keyword landing_page
-- ------- --------------------------------------
-- apple https://www.example.co.uk/
-- apple https://www.example.co.uk/landing-page
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